when did the first true multi-cellular organisms with true tissues evolve

Multicellularity has evolved independently at least 46 times,[5][6] including in some prokaryotes, like cyanobacteria, myxobacteria, actinomycetes, Magnetoglobus multicellularis or Methanosarcina. However, complex multicellular organisms evolved only in six eukaryotic groups: animals, fungi, brown algae, red algae, green algae, and land plants.[7] It evolved repeatedly for Chloroplastida (green algae and land plants), once or twice for animals, once for brown algae, three times in the fungi (chytrids, ascomycetes and basidiomycetes)[8] and perhaps several times for slime molds and red algae.[9] The first evidence of multicellularity is from cyanobacteria-like organisms that lived 3–3.5 billion years ago.[5] To reproduce, true multicellular organisms must solve the problem of regenerating a whole organism from germ cells (i.e. sperm and egg cells), an issue that is studied in evolutionary developmental biology. Animals have evolved a considerable diversity of cell types in a multicellular body (100–150 different cell types), compared with 10–20 in plants and fungi.[10]

Multicellular organism

Multicellular organisms are organisms that consist of more than one cell, in contrast to unicellular organisms.[1]

All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus Dictyostelium.

Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells.[2] Colonial organisms are the result of many identical individuals joining together to form a colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular".[3][4]

Loss of multicellularity occurred in some groups.[11] Fungi are predominantly multicellular, though early diverging lineages are largely unicellular (e.g. Microsporidia) and there have been numerous reversions to unicellularity across fungi (e.g. Saccharomycotina, Cryptococcus, and other yeasts).[12][13] It may also have occurred in some red algae (e.g. Porphyridium), but it is possible that they are primitively unicellular.[14] Loss of multicellularity is also considered probable in some green algae (e.g. Chlorella vulgaris and some Ulvophyceae).[15][16] In other groups, generally parasites, a reduction of multicellularity occurred, in number or types of cells (e.g. the myxozoans, multicellular organisms, earlier thought to be unicellular, are probably extremely reduced cnidarians).[17]

Multicellular organisms, especially long-living animals, face the challenge of cancer, which occurs when cells fail to regulate their growth within the normal program of development. Changes in tissue morphology can be observed during this process. Cancer in animals (metazoans) has often been described as a loss of multicellularity.[18] There is a discussion about the possibility of existence of cancer in other multicellular organisms[19][20] or even in protozoa.[21] For example, plant galls have been characterized as tumors[22] but some authors argue that plants do not develop cancer.[23]

In some multicellular groups, which are called Weismannists, a separation between a sterile somatic cell line and a germ cell line evolved. However, Weismannist development is relatively rare (e.g. vertebrates, arthropods, Volvox), as great part of species have the capacity for somatic embryogenesis (e.g. land plants, most algae, many invertebrates).[24][25]

One hypothesis for the origin of multicellularity is that a group of function-specific cells aggregated into a slug-like mass called a grex, which moved as a multicellular unit. This is essentially what slime molds do. Another hypothesis is that a primitive cell underwent nucleus division, thereby becoming a coenocyte. A membrane would then form around each nucleus (and the cellular space and organelles occupied in the space), thereby resulting in a group of connected cells in one organism (this mechanism is observable in Drosophila). A third hypothesis is that as a unicellular organism divided, the daughter cells failed to separate, resulting in a conglomeration of identical cells in one organism, which could later develop specialized tissues. This is what plant and animal embryos do as well as colonial choanoflagellates.[26][27]

Because the first multicellular organisms were simple, soft organisms lacking bone, shell or other hard body parts, they are not well preserved in the fossil record.[28] One exception may be the demosponge, which may have left a chemical signature in ancient rocks. The earliest fossils of multicellular organisms include the contested Grypania spiralis and the fossils of the black shales of the Palaeoproterozoic Francevillian Group Fossil B Formation in Gabon (Gabonionta).[29] The Doushantuo Formation has yielded 600 million year old microfossils with evidence of multicellular traits.[30]

Until recently, phylogenetic reconstruction has been through anatomical (particularly embryological) similarities. This is inexact, as living multicellular organisms such as animals and plants are more than 500 million years removed from their single-cell ancestors. Such a passage of time allows both divergent and convergent evolution time to mimic similarities and accumulate differences between groups of modern and extinct ancestral species. Modern phylogenetics uses sophisticated techniques such as alloenzymes, satellite DNA and other molecular markers to describe traits that are shared between distantly related lineages.

The evolution of multicellularity could have occurred in a number of different ways, some of which are described below:

This theory suggests that the first multicellular organisms occurred from symbiosis (cooperation) of different species of single-cell organisms, each with different roles. Over time these organisms would become so dependent on each other they would not be able to survive independently, eventually leading to the incorporation of their genomes into one multicellular organism.[31] Each respective organism would become a separate lineage of differentiated cells within the newly created species.

This kind of severely co-dependent symbiosis can be seen frequently, such as in the relationship between clown fish and Riterri sea anemones. In these cases, it is extremely doubtful whether either species would survive very long if the other became extinct. However, the problem with this theory is that it is still not known how each organism's DNA could be incorporated into one single genome to constitute them as a single species. Although such symbiosis is theorized to have occurred (e.g. mitochondria and chloroplasts in animal and plant cellsâ€”endosymbiosis), it has happened only extremely rarely and, even then, the genomes of the endosymbionts have retained an element of distinction, separately replicating their DNA during mitosis of the host species. For instance, the two or three symbiotic organisms forming the composite lichen, although dependent on each other for survival, have to separately reproduce and then re-form to create one individual organism once more.

This theory states that a single unicellular organism, with multiple nuclei, could have developed internal membrane partitions around each of its nuclei.[32] Many protists such as the ciliates or slime molds can have several nuclei, lending support to this hypothesis. However, the simple presence of multiple nuclei is not enough to support the theory. Multiple nuclei of ciliates are dissimilar and have clear differentiated functions. The macronucleus serves the organism's needs, whereas the micronucleus is used for sexual reproduction with exchange of genetic material. Slime molds syncitia form from individual amoeboid cells, like syncitial tissues of some multicellular organisms, not the other way round. To be deemed valid, this theory needs a demonstrable example and mechanism of generation of a multicellular organism from a pre-existing syncytium.

The Colonial Theory of Haeckel, 1874, proposes that the symbiosis of many organisms of the same species (unlike the symbiotic theory, which suggests the symbiosis of different species) led to a multicellular organism. At least some, it is presumed land-evolved, multicellularity occurs by cells separating and then rejoining (e.g. cellular slime molds) whereas for the majority of multicellular types (those that evolved within aquatic environments), multicellularity occurs as a consequence of cells failing to separate following division.[33] The mechanism of this latter colony formation can be as simple as incomplete cytokinesis, though multicellularity is also typically considered to involve cellular differentiation.[34]

The advantage of the Colonial Theory hypothesis is that it has been seen to occur independently in 16 different protoctistan phyla. For instance, during food shortages the amoeba Dictyostelium groups together in a colony that moves as one to a new location. Some of these amoeba then slightly differentiate from each other. Other examples of colonial organisation in protista are Volvocaceae, such as Eudorina and Volvox, the latter of which consists of up to 500–50,000 cells (depending on the species), only a fraction of which reproduce.[35] For example, in one species 25–35 cells reproduce, 8 asexually and around 15–25 sexually. However, it can often be hard to separate colonial protists from true multicellular organisms, as the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular".[3]

Some authors suggest that the origin of multicellularity, at least in Metazoa, occurred due to a transition from temporal to spatial cell differentiation, rather than through a gradual evolution of cell differentiation, as affirmed in Haeckelâ€™s Gastraea theory.[36]

About 800 million years ago,[37] a minor genetic change in a single molecule called guanylate kinase protein-interaction domain (GK-PID) may have allowed organisms to go from a single cell organism to one of many cells.[38]

Genes borrowed from viruses have recently been identified as playing a crucial role in the differentiation of multicellular tissues and organs and even in sexual reproduction, in the fusion of egg cell and sperm. Such fused cells are also involved in metazoan membranes such as those that prevent chemicals crossing the placenta and the brain body separation. Two viral components have been identified. The first is syncytin, which came from a virus. The second identified in 2007 is called EFF1, which helps form the skin of Caenorhabditis elegans, part of a whole family of FF proteins. Felix Rey, of the Pasteur Institute in Paris has constructed the 3D structure of the EFF1 protein[39] and shown it does the work of linking one cell to another, in viral infections. The fact that all known cell fusion molecules are viral in origin suggests that they have been vitally important to the inter-cellular communication systems that enabled multicellularity. Without the ability of cellular fusion, colonies could have formed, but anything even as complex as a sponge would not have been possible.[40]

Multicellularity allows an organism to exceed the size limits normally imposed by diffusion: single cells with increased size have a decreased surface-to-volume ratio and have difficulty absorbing sufficient nutrients and transporting them throughout the cell. Multicellular organisms thus have the competitive advantages of an increase in size without its limitations. They can have longer lifespans as they can continue living when individual cells die. Multicellularity also permits increasing complexity by allowing differentiation of cell types within one organism.


who sang i will follow him in sister act

The song is featured at the end of the 1992 film Sister Act, where it was performed by the nuns' chorus for the Pope.[15]

I Will Follow Him

"I Will Follow Him" is a popular song that was first recorded in 1961 by Franck Pourcel, as an instrumental titled "Chariot". The song achieved its widest success when it was recorded by American singer Little Peggy March with English lyrics in 1963. The music was written by Franck Pourcel (using the pseudonym J.W. Stole) and Paul Mauriat (using the pseudonym Del Roma).[1] It was adapted by Arthur Altman. The English lyrics were written by Norman Gimbel.[2]

The song was first recorded in 1961 by Franck Pourcel and began as an instrumental piece appearing on the 1961 European LP release Amour, Danse, Et Violons. No.17. At the same time, it appeared on the EP release La Voix de son Maître. Pourcel co-wrote the song with his friend and fellow French bandleader Paul Mauriat.[1] The other French bandleader Raymond Lefèvre has been credited for arrangements. Franck Pourcel's original recording was popular on MOR, or "easy listening," stations. Mauriat later recorded an instrumental version in 1976 with a disco beat, using a Moog synthesizer.

In 1963, Percy Faith released an instrumental version, re-titled "I Will Follow You", as the lead song on side 1 of his album titled Themes for Young Lovers.[3][4] Many other hits at the time were also on the album, including "Up on the Roof", "On Broadway", and "Rhythm of the Rain".[3]

In 1962, Petula Clark released a French language version of the song, titled "Chariot" (lyrics by Jacques Plante),[1] which reached No. 1 in Wallonia,[5][6] No. 2 in France,[7] and No. 8 in Flanders,[8][9] and earned Clark a gold record. Her English version reached No. 4 in Denmark, where it was released by Vogue,[10] but failed to chart in the UK and the USA, where it was released by Pye and Laurie respectively. Clark also recorded Italian and German versions of the song, with her Italian version, "Sul mio carro", reaching No. 4 in Italy,[11] and her German version, "Cheerio", reaching No. 6 in West Germany.[12]

In 1963, Little Peggy March's version of "I Will Follow Him", backed with "Wind Up Doll", was released by RCA Victor.[13] March's version spent 14 weeks on the Billboard Hot 100, reaching No. 1 on April 27, 1963 and spending three weeks in this position,[14] making 15-year-old March the youngest female artist to have a U.S. chart-topping single.[15] Her version also reached No. 1 in Australia,[16] Hong Kong,[17] Israel,[18] South Africa,[10] Uruguay,[19] Canada's CHUM Hit Parade,[20] New Zealand's "Lever Hit Parade",[21] and Billboard's Hot R&B Singles chart.[22][23]

The song also reached No. 1 on the Cash Box Top 100, in a tandem ranking of Little Peggy March, Franck Pourcel, Petula Clark, Rosemary Clooney, Betty Curtis, Jackie Kannon, Joe Sentieri, and Georgia Gibbs' versions, with March's version marked as a bestseller.[24]

In Italy three versions of the song were in the charts in 1963 (translated/adapted by Vito Pallavicini and Bruno Pallesi): One recorded by Betty Curtis (highest position: No. 3), another version by Petula Clark ("Sul mio carro"; No. 4) and the Franck Pourcel version (No. 5).[11] The song reached No. 1 in Italy's Musica e dischi, in a tandem ranking of these three versions.[34] Curtis's version was also a top 10 hit in Uruguay.[35]

In 1963, Italian singer Ennio Sangiusto released a version of the song titled "Chariot (La Tierra)", which reached No. 1 in Spain.[18] Also in 1963, Italian singer Joe Sentieri released a version of the song titled "La Tierra", which reached No. 3 in Argentina.[36]

In 1963, Argentine singer Alberto Cortez released a version of the song titled "La Tierra (Chariot)", which reached No. 2 in Spain.[37] Also in 1963, Argentine singer Violeta Rivas released a version titled "La Tierra", which reached No. 1 in Uruguay.[38]

Dee Dee Sharp released a version of the song on her 1963 album Do the Bird.[39] Sharp's version reached No. 1 in Hong Kong.[27]

In 1982, Dutch singer José Hoebee (former member of the girl band Luv') released a hit cover of the song, which reached No. 1 in Flanders,[40] No. 1 on the Dutch Top 40,[41] and No. 2 on the Dutch Nationale Hitparade.[42] A new version, recorded in 2005, reached No. 90 on the Dutch Single Top 100.[43]

In 1994, Spanish singer Raphael released a Spanish version of the song titled "La Tierra" (English: "The Earth"), which appeared on his album FantasÃa.[44] Raphael performed the song in his tours with remarkable success until 1999.

The Norwegian comedian Lars Mjøen wrote comedic Norwegian lyrics, «Torsken kommer!» (translates to «The cod is coming»). The song was published by the comedy troupe KLM as Brødrene Dal as the B-side of "Gaus, Roms Og Brumund" (PolyGram 2052 206)[45][46] and on the LP record Spektralplate (Polydor 2382 135) in 1982. A music video remake was released by Norges Bank in 2017 to mark the introduction of the new 200 krone banknote that features a cod on the obverse side.[47]

In 2009, Swedish singer Jessica Andersson covered it on her album, Wake Up.[48]

The song is also used by Malaysian mobile service provider Digi for its extensive promotional campaign in late 2006, albeit with slightly different lyrics (as "I Will Follow You").[49] The first five notes of the song has since been made into the main jingle for future Digi advertisements.


who played john in hush hush sweet charlotte

In 1927, young Southern belle Charlotte Hollis (Bette Davis) and her married lover, John Mayhew (Bruce Dern), plan to elope during a party at the Hollis family's antebellum mansion in Ascension Parish, Louisiana. Charlotte's father confronts John over the affair and intimidates him with the news that John's wife, Jewel, visited the day before and revealed the affair. John pretends he no longer loves Charlotte and tells her they must part.

Hush… Hush, Sweet Charlotte

Hush...Hush, Sweet Charlotte is a 1964 American psychological thriller film directed and produced by Robert Aldrich,[4] and starring Bette Davis, Olivia de Havilland, Joseph Cotten, Agnes Moorehead and Mary Astor in her final film role.[5]

The movie was adapted for the screen by Henry Farrell and Lukas Heller, from Farrell's unpublished short story, "What Ever Happened to Cousin Charlotte?" It received seven Academy Award nominations.

John is then brutally murdered and decapitated in the summerhouse with a cleaver, with one hand severed. Charlotte discovers his body. She returns traumatized to the party in a bloody dress, and most of the guests assume Charlotte is the murderer.

The story jumps to 1964. Charlotte is now a wealthy spinster, still living on the Ascension Parish plantation that has been in her family for generations. Charlotte's father died the year after Mayhew's murder, believing his daughter guilty. All these years, Charlotte has believed that her father killed John Mayhew. Everyone else assumes that Charlotte, the crazy recluse, decapitated her lover.

The Louisiana Highway Commission intends to demolish her house and build a new highway through the plantation. Charlotte is vehemently against this and ignores the eviction notice, refusing to leave. She keeps the foreman (George Kennedy), his demolition crew, and the bulldozer away by shooting at them with a rifle. They temporarily give up and leave.

Charlotte is living alone as a virtual recluse in the Hollis mansion, tended by Velma (Agnes Moorehead) her housekeeper. Seeking help in her fight against the Highway Commission, she calls upon Miriam (Olivia de Havilland), a poor cousin who lived with the family as a girl, but who has since moved to New York City and has become wealthy herself. Miriam renews her relationship with Drew Bayliss (Joseph Cotten), a local doctor who jilted her after the murder.

Charlotte's sanity deteriorates with Miriam's arrival, her nights haunted by a mysterious harpsichord playing the song Mayhew wrote for her and by the appearance of Mayhew's disembodied hand and head. Suspecting that Miriam and Drew are after Charlotte's money, Velma seeks help from Mr. Willis (Cecil Kellaway), an insurance investigator who is still interested in the Mayhew case and has visited Mayhew's ailing widow, Jewel (Mary Astor).

Miriam fires Velma, who later returns to discover that Charlotte is being drugged. Miriam sees the housekeeper trying to take Charlotte out of the house. The two argue at the top of the stairs. Velma tries to escape, but knowing that Velma has discovered the drugs, Miriam smashes a chair over her head. Velma falls down the stairs to her death.

One night, a drugged Charlotte runs downstairs in the grip of a hallucination, believing John has returned to her. Miriam and Drew decide to trick Charlotte into shooting Drew with a gun loaded with blanks, after which Miriam helps dispose of the "body" in a swamp. Charlotte returns to the house and sees the supposedly dead Drew at the top of the stairs, reducing her to whimpering insanity.

Now believing Charlotte completely mad and secure in her room, Miriam and Drew go into the garden to discuss their plan: to drive Charlotte insane in order to get her money. Miriam also tells Drew that back in 1927 she saw Jewel murder her husband. She's been using this knowledge to blackmail Jewel for all these years, while plotting to gain possession of Charlotte's wealth.

Charlotte overhears all. She moves toward a huge stone urn on the ledge of the balcony, almost directly over the lovers' heads. Miriam embraces Drew, then she looks up and is paralyzed by the sight of Charlotte tipping the stone urn off the ledge, crushing both to death.

The next morning the authorities take Charlotte away, presumably to an insane asylum or possibly to a new home for herself. Many neighbors and locals gather at the Hollis home to watch the proceedings, believing that crazy Charlotte has murdered again. But some are very complimentary and sympathetic towards her. Willis hands her an envelope from the now-dead Jewel Mayhew, who has had a stroke after hearing of the incident the previous night. The envelope contains Jewel's confession to the murder of her husband. As the authorities drive Charlotte away, she looks back at her beloved plantation.

Following the unexpected box-office success of What Ever Happened to Baby Jane? (1962), director Robert Aldrich wanted to make a film on similar themes that reunited stars Joan Crawford and Bette Davis. Writer Henry Farrell, on whose novel the film had been based, had also written an unpublished short story called "What Ever Happened to Cousin Charlotte?" that seemed to make an excellent followup. It told a similar story of a woman who manipulates a relative for personal gain, but for this film, Aldrich's idea was that the two actresses would essentially switch the roles from the previous one, with Crawford playing the devious cousin trying to manipulate the innocent Davis into giving up her estate.[6]

However, Davis was incensed when Crawford accepted Anne Bancroft's Oscar for The Miracle Worker on the absent winner's behalf at that year's ceremony, an award Davis had been nominated for but not Crawford. She believed Crawford had somehow ensured Bancroft would win just so she could upstage her costar and rival. So, after asking Aldrich if he had been having a sexual relationship with Crawford (much as Crawford had asked the director the same question about him and Davis before Baby Jane), she agreed to take the role only if she got a producing credit.[6]

Aware of this, Crawford was convinced that Davis was trying to undermine her in retaliation for the Oscar-night humiliation. Her suspicions only increased when no one came to pick her up at the airport in Baton Rouge for the film's principal photography location shooting. Davis was in fact making crew members decide whether they were with her or Crawford, and wound up with support even from those who had known and worked with Crawford for a long time due to her imperious behavior on the shoot. On the last day of filming on location, Crawford, who had gone back to her trailer and fallen asleep there in case she was needed for anything extra, awoke to find everyone had left her behind, having gone back to the hotel after wrapping.[6]

Crawford was convinced Davis had engineered this, and upon returning to Hollywood where production was to continue on set announced after one day that she was sickâ€”at first a ploy to get changes made to the script, but then she actually convinced herself she was sick. Production was mostly suspended to allow her to recover, and she returned for a day, but then after two months, during which a private investigator trailed her to see whether she was really sick or not, the producers were told that either Crawford would be replaced or the production would be canceled. After Aldrich spent four days at Olivia de Havilland's home in Switzerland, she agreed to take the part. Crawford later complained that she only learned of her firing during the news on the radio.[6]

Three other cast members from What Ever Happened to Baby Jane? did appear in Hush...Hush, Sweet Charlotte: Wesley Addy, Dave Willock (as a taxi driver) and Victor Buono. The cast also included Mary Astor, a friend and former co-worker of Davis' during her time at Warner Bros.[4]

Scenes outside the Hollis mansion were shot on location at Houmas House plantation in Louisiana.[7][8] The inside scenes were shot on a soundstage in Hollywood.

Hush...Hush, Sweet Charlotte was another hit for Aldrich, opening to positive reviews. A pan, however, came from The New York Times. Bosley Crowther observed, "So calculated and coldly carpentered is the tale of murder, mayhem and deceit that Mr. Aldrich stages in this mansion that it soon appears grossly contrived, purposely sadistic and brutally sickening. So, instead of coming out funny, as did Whatever Happened to Baby Jane?, it comes out grisly, pretentious, disgusting and profoundly annoying."[9]

Variety's reviewer wrote: "Davis' portrayal is reminiscent of Jane in its emotional overtones, in her style of characterization of the near-crazed former Southern belle, aided by haggard makeup and outlandish attire. It is an outgoing performance, and she plays it to the limit. De Havilland, on the other hand, is far more restrained but nonetheless effective dramatically in her offbeat role."[10]

Time Out London observed: "Over the top, of course, and not a lot to it, but it's efficiently directed, beautifully shot, and contains enough scary sequences amid the brooding, tense atmosphere. Splendid performances from Davis and Moorehead, too."[11]

Judith Crist wrote about the film, "The guignol is about as grand as it gets."

Kenneth Tynan asserted that "(Davis) has done nothing better since The Little Foxes."

The film maintains a 85% rating on review aggregation website Rotten Tomatoes based on 20 reviews.[12]

Hush...Hush, Sweet Charlotte received Academy Award nominations for the following:

Moorehead won the Golden Globe Award for Best Supporting Actress. Farrell and Heller won a 1965 Edgar Award, from the Mystery Writers of America, for Best Motion Picture Screenplay. The title song became a hit for Patti Page, who took it to No. 8 on the Billboard Hot 100. The film's seven Oscar nominations were the most for a movie of the horror genre up to that time.

Hush...Hush, Sweet Charlotte was first released on DVD on August 9, 2005. It was re-released on April 8, 2008 as part of The Bette Davis Centenary Celebration Collection 5-DVD box-set.[14]

On October 17, 2016, Hush...Hush Sweet Charlotte was released onto high-definition Blu-ray by Twilight Time as a 3000-print limited edition.[15]


what is the name associated with modern paper making machines

A paper machine (or paper-making machine) is an industrial machine used in the Pulp and paper industry
to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.

Paper machine

The basic process is an industrialised version of the historical process of hand paper-making, which could not satisfy the demands of developing modern society for large quantities of a printing and writing substrate. The first modern paper machine was invented in Britain by Henry and Sealy Fourdrinier, and patented in 1806.

The same process is used to produce paperboard on a paperboard machine.

Paper machines usually have at least five distinct operational sections:

There can also be a coating section to modify the surface characteristics with coatings such as china clay.

Before the invention of continuous paper making, paper was made in individual sheets by stirring a container of pulp slurry and either pouring it into a fabric sieve called a sheet mould or dipping and lifting the sheet mould from the vat. While still on the fabric in the sheet mould, the wet paper is pressed to remove excess water and then the sheet is lifted off to be hung over a rope or wooden rod to air dry.

In 1799, Louis-Nicolas Robert of Essonnes, France, was granted a patent for a continuous paper making machine.[1] At the time Robert was working for Saint-Léger Didot, with whom he quarreled over the ownership of the invention. Didot thought that England was a better place to develop the machine. But during the troubled times of the French Revolution, he could not go there himself, so he sent his brother-in-law, John Gamble, an Englishman living in Paris. Through a chain of acquaintances, Gamble was introduced to the brothers Sealy and Henry Fourdrinier, stationers of London, who agreed to finance the project. Gamble was granted British patent 2487 on 20 October 1801. The Fourdrinier machine used a specially woven plastic fabric mesh conveyor belt (known as a wire, as it was once woven from bronze) in the forming section, where a slurry of fibre (usually wood or other vegetable fibres) is drained to create a continuous paper web. The original Fourdrinier forming section used a horizontal drainage area, referred to as the drainage table.

With the help particularly of Bryan Donkin, a skilled and ingenious mechanic, an improved version of the Robert original was installed at Frogmore Paper Mill, Apsley, Hertfordshire, in 1803, followed by another in 1804. A third machine was installed at the Fourdriniers' own mill at Two Waters. The Fourdriniers also bought a mill at St Neots intending to install two machines there and the process and machines continued to develop.

Thomas Gilpin is most often credited for creating the first U.S cylinder type papermaking machine at Brandywine Creek, Delaware in 1817. This machine was also developed in England, but it was a cylinder mould machine. The Fourdrinier machine wasn't introduced into the USA until 1827.[2]

Records show Charles Kinsey of Paterson, NJ had already patented a continuous process papermaking machine in 1807.  Kinsey’s machine was built locally by Daniel Sawn and by 1809 the Kinsey machine was successfully making paper at the Essex Mill in Paterson.  Financial stress and potential opportunities created by the Embargo of 1807 eventually persuaded Kinsey and his backers to change the mill’s focus from paper to cotton and Kinsey's early papermaking successes were soon overlooked and forgotten.[3][4]

Gilpin's 1817 patent was similar to Kinsey's, as was the John Ames patent of 1822.  The Ames patent was challenged by his competitors, asserting that Kinsey was the original inventor and Ames had been pilfering other peoples' ideas, their evidence being the employment of Daniel Sawn to work on his machine.[3]

The method of continuous production demonstrated by the paper machine influenced the development of continuous rolling of iron and later steel and other continuous production processes.[5]

The plant fibres used for pulp are composed mostly of cellulose and hemi-cellulose, which have a tendency to form molecular linkages between fibres in the presence of water.  After the water evaporates the fibres remain bonded.  It is not necessary to add additional binders for most paper grades, although both wet and dry strength additives may be added.

Rags of cotton and linen were the major source of pulp for paper before wood pulp.  Today almost all pulp is of wood fibre.  Cotton fibre is used in speciality grades, usually in printing paper for such things as resumes and currency.

Sources of rags often appear as waste from other manufacturing such as denim fragments or glove cuts.  Fibres from clothing come from the cotton boll.  The fibres can range from 3 to 7Â cm in length as they exist in the cotton field.  Bleach and other chemicals remove the colour from the fabric in a process of cooking, usually with steam.  The cloth fragments mechanically abrade into fibres, and the fibres get shortened to a length appropriate for manufacturing paper with a cutting process.  Rags and water dump into a trough forming a closed loop.  A cylinder with cutting edges, or knives, and a knife bed is part of the loop. The spinning cylinder pushes the contents of the trough around repeatedly.  As it lowers slowly over a period of hours, it breaks the rags up into fibres, and cuts the fibres to the desired length.  The cutting process terminates when the mix has passed the cylinder enough times at the programmed final clearance of the knives and bed.

Another source of cotton fibre comes from the cotton ginning process.  The seeds remain, surrounded by short fibres known as linters for their short length and resemblance to lint.  Linters are too short for successful use in fabric.  Linters removed from the cotton seeds are available as first and second cuts.  The first cuts are longer.

The two major classifications of pulp are chemical and mechanical.  Chemical pulps formerly used a sulphite process, but the kraft process is now predominant.  Kraft pulp has superior strength to sulphite and mechanical pulps.  Both chemical pulps and mechanical pulps may be bleached to a high brightness.

Chemical pulping dissolves the lignin that bonds fibres to one another, and binds the outer fibrils that compose individual fibres to the fibre core.  Lignin, like most other substances that can separate fibres from one another, acts as a debonding agent, lowering strength.  Strength also depends on maintaining long cellulose molecule chains.  The kraft process, due to the alkali and sulphur compounds used, tends to minimize attack on the cellulose and the non-crystalline hemicellulose, which promotes bonding, while dissolving the lignin. Acidic pulping processes shorten the cellulose chains.

Kraft pulp makes superior linerboard and excellent printing and writing papers.

Groundwood, the main ingredient used in newsprint and a principal component of magazine papers (coated publications), is literally ground wood produced by a grinder.  Therefore, it contains a lot of lignin, which lowers its strength.  The grinding produces very short fibres that drain slowly.

Thermomechanical pulp (TMP) is a variation of groundwood where fibres are separated mechanically while at high enough temperatures to soften the lignin.

Between chemical and mechanical pulps there are semi-chemical pulps that use a mild chemical treatment followed by refining.  Semi-chemical pulp is often used for corrugating medium.

Bales of recycled paper (normally old corrugated containers) for unbleached (brown) packaging grades may be simply pulped, screened and cleaned.  Recycling to make white papers is usually done in a deinking plant, which employs screening, cleaning, washing, bleaching and flotation. Deinked pulp is used in printing and writing papers and in tissue, napkins and paper towels. It is often blended with virgin pulp.

At integrated pulp and paper mills, pulp is usually stored in high density towers before being pumped to stock preparation.  Non integrated mills use either dry pulp or wet lap (pressed) pulp, usually received in bales.  The pulp bales are slushed in a [re]pulper.

Stock preparation is the area where pulp is usually refined, blended to the appropriate proportion of hardwood, softwood or recycled fibre, and diluted to as uniform and constant as possible consistency. The pH is controlled and various fillers, such as whitening agents, size and wet strength or dry strength are added if necessary.  Additional fillers such as clay, calcium carbonate and titanium dioxide increase opacity so printing on reverse side of a sheet will not distract from content on the obverse side of the sheet.  Fillers also improve printing quality.[6]

Pulp is pumped through a sequence of tanks that are commonly called chests, which may be either round or more commonly rectangular.  Historically these were made of special ceramic tile faced reinforced concrete, but mild and stainless steels are also used.  Low consistency pulp slurries are kept agitated in these chests by propeller like agitators near the pump suction at the chest bottom.

In the following process, different types of pulp, if used, are normally treated in separate but similar process lines until combined at a blend chest:

From high density storage or from slusher/pulper the pulp is pumped to a low density storage chest (tank).  From there it is typically diluted to about 4% consistency before being pumped to an unrefined stock chest.  From the unrefined stock chest stock is again pumped, with consistency control, through a refiner.  Refining is an operation whereby the pulp slurry passes between a pair of discs, one of which is stationary and the other rotating at speeds of typically 1,000 or 1,200 RPM for 50 and 60Â Hz AC, respectively.  The discs have raised bars on their faces and pass each other with narrow clearance.  This action unravels the outer layer of the fibres, causing the fibrils of the fibres to partially detach and bloom outward, increasing the surface area to promoting bonding. Refining thus increases tensile strength.  For example, tissue paper is relatively unrefined whereas packaging paper is more highly refined. Refined stock from the refiner then goes to a refined stock chest, or blend chest, if used as such.

Hardwood fibres are typically 1 mm long and smaller in diameter than the 4 mm length typical of softwood fibres. Refining can cause the softwood fibre tube to collapse resulting in undesirable properties in the sheet.

From the refined stock, or blend chest, stock is again consistency controlled as it is being pumped to a machine chest. It may be refined or additives may be added en route to the machine chest.

The machine chest is basically a consistency levelling chest having about 15 minutes retention. This is enough retention time to allow any variations in consistency entering the chest to be levelled out by the action of the basis weight valve receiving feedback from the on line basis weight measuring scanner. (Note: Many paper machines mistakenly control consistency coming out of the machine chest, interfering with basis weight control.)[7]

There are four main sections on this paper machine. The forming section makes the pulp into the basis of for sheets along the wire. The press section, which removes much of the remaining water via a system of nips formed by rolls pressing against each other aided by press felts that support the sheet and absorb the pressed water. The dryer section of the paper machine, as its name suggests, dries the paper by way of a series of internally steam-heated cylinders that evaporate the moisture. Calenders are used to make the paper surface extra smooth and glossy. In practice calender rolls are normally placed vertically in a stack.

From the machine chest stock is pumped to a head tank, commonly called a "head tank" or stuff box, whose purpose is to maintain a constant head (pressure) on the fiber slurry or stock as it feeds the basis weight valve.  The stuff box also provides a means allowing air bubbles to escape. The consistency of the pulp slurry at the stuff box is in the 3% range.  Flow from the stuff box is by gravity and is controlled by the basis weight valve on its way to the fan pump suction where it injected into main flow of water to the fan pump.  The main flow of water pumped by the fan pump is from a whitewater chest or tank that collects all the water drained from the forming section of the paper machine. Before the fiber stream from the stuff box is introduced, the whitewater is very low in fiber content.  The whitewater is constantly recirculated by the fan pump through the headbox and recollected from the wire pit and various other tanks and chests that receive drainage from the forming wire and vacuum assisted drainage from suction boxes and wet fiber web handling rolls.  On the way to the head box the pulp slurry may pass through centrifugal cleaners, which remove heavy contaminants like sand, and screens, which break up fibre clumps and remove over-sized debris. The fan pump ultimately feeds the headbox, whether or not any centrifugal cleaners or screens are present.[8][9][10]

The purpose of the headbox is create turbulence to keep the fibers from clumping together and to uniformly distribute the slurry across the width of the wire. Wood fibers have a tendency to attract one another, forming clumps, the effect being called flocculation.  Flocculation is lessened by lowering consistency and or by agitating the slurry; however, de-flocculation becomes very difficult at much above 0.5% consistency.  Minimizing the degree of flocculation when forming is important to physical properties of paper.[9][10]

The consistency in the headbox is typically under 0.4% for most paper grades, with longer fibres requiring lower consistency than short fibres.  Higher consistency causes more fibres to be oriented in the z direction, while lower consistency promotes fibre orientation in the x-y direction. Higher consistency promotes higher calliper (thickness) and stiffness, lower consistency promotes higher tensile and some other strength properties and also improves formation (uniformity).[9][10]  Many sheet properties continue to improve down to below 0.1% consistency; however, this is an impractical amount of water to handle. (Most paper machine run a higher headbox consistency than optimum because they have been sped up over time without replacing the fan pump and headbox. There is also an economic trade off with high pumping costs for lower consistency).

The stock slurry, often called white water at this point, exits the head box through a rectangular opening of adjustable height called the slice, the white water stream being called the jet and it is pressurized on high speed machines so as to land gently on the moving fabric loop or wire at a speed typically between plus or minus 3% of the wire speed, called rush and drag respectively.  Excessive rush or drag causes more orientation of fibres in the machine direction and gives differing physical properties in machine and cross directions; however, this phenomenon is not completely avoidable on Fourdrinier machines.[9][10]

On lower speed machines at 700 feet per minute, gravity and the height of the stock in the headbox creates sufficient pressure to form the jet through the opening of the slice.  The height of the stock is the head, which gives the headbox its name.  The speed of the jet compared to the speed of the wire is known as the jet-to-wire ratio.  When the jet-to-wire ratio is less than unity, the fibres in the stock become drawn out in the machine direction.  On slower machines where sufficient liquid remains in the stock before draining out, the wire can be driven back and forth with a process known as shake.  This provides some measure of randomizing the direction of the fibres and gives the sheet more uniform strength in both the machine and cross-machine directions.  On fast machines, the stock does not remain on the wire in liquid form long enough and the long fibres line up with the machine.  When the jet-to-wire ratio exceeds unity, the fibers tend to pile up in lumps.[9][10]  The resulting variation in paper density provides the antique or parchment paper look.

Two large rolls typically form the ends of the drainage section, which is called the drainage table.  The breast roll is located under the flow box, the jet being aimed to land on it at about the top centre.  At the other end of the drainage table is the suction (couch) roll.  The couch roll is a hollow shell, drilled with many thousands of precisely spaced holes of about 4 to 5Â mm diameter.  The hollow shell roll rotates over a stationary suction box, normally placed at the top centre or rotated just down machine.  Vacuum is pulled on the suction box, which draws water from the web into the suction box.  From the suction roll the sheet feeds into the press section.[9][10]

Down machine from the suction roll, and at  a lower elevation, is the wire turning roll. This roll is driven and pulls the wire around the loop. The wire turning roll has a considerable angle of wrap in order to grip the wire.[9]

Supporting the wire in the drainage table area are a number of drainage elements.  In addition to supporting the wire and promoting drainage, the elements de-flocculate the sheet.  On low speed machines these table elements are primarily table rolls.  As speed increases the suction developed in the nip of a table roll increases and at high enough speed the wire snaps back after leaving the vacuum area and causes stock to jump off the wire, disrupting the formation.  To prevent this drainage foils are used.  The foils are typically sloped between zero and two or three degrees and give a more gentle action.  Where rolls and foils are used, rolls are used near the headbox and foils further down machine.[9][10]

Approaching the dry line on the table are located low vacuum boxes that are drained by a barometric leg under gravity pressure. After the dry line are the suction boxes with applied vacuum.  Suction boxes extend up to the couch roll.  At the couch the sheet consistency should be about 25%.[9][10]

The forming section type is usually based on the grade of paper or paperboard being produced; however, many older machines use a less than optimum design.  Older machines can be upgraded to include more appropriate forming sections.

A second headbox may be added to a conventional fourdrinier to put a different fibre blend on top of a base layer.  A secondary headbox is normally located at a point where the base sheet is completely drained.  This is not considered a separate ply because the water action does a good job of intermixing the fibers of the top and bottom layer.  Secondary headboxes are common on linerboard.

A modification to the basic fourdrinier table by adding a second wire on top of the drainage table is known as a top wire former.  The bottom and top wires converge and some drainage is up through the top wire.  A top wire improves formation and also gives more drainage, which is useful for machines that have been sped up.

The Twin Wire Machine or Gap former uses two vertical wires in the forming section, thereby increasing the de-watering rate of the fibre slurry while also giving uniform two sidedness.[11]

There are also machines with entire Fourdrinier sections mounted above a traditional Fourdrinier. This allows making multi-layer paper with special characteristics.  These are called top Fourdriniers and they make multi-ply paper or paperboard. Commonly this is used for making a top layer of bleached fibre to go over an unbleached layer.

Another type forming section is the cylinder mould machine[12] using a mesh-covered rotating cylinder partially immersed  in a tank of fibre slurry in the wet end to form a paper web, giving a more random distribution of the cellulose fibres. Cylinder machines can form a sheet at higher consistency, which gives a more three dimensional fibre orientation than lower consistencies, resulting in higher calliper (thickness) and more stiffness in the machine direction (MD).  High MD stiffness is useful in food packaging like cereal boxes and other boxes like dry laundry detergent.

Tissue machines typically form the paper web between a wire and a special fabric (felt) as they wrap around a forming roll.  The web is pressed from the felt directly onto a large diameter dryer called a yankee.  The paper sticks to the yankee dryer and is peeled off with a scraping blade called a doctor.  Tissue machines operate at speeds of up to 2000Â m/min.

The second section of the paper machine is the press section, which removes much of the remaining water via a system of nips formed by rolls pressing against each other aided by press felts that support the sheet and absorb the pressed water.  The paper web consistency leaving the press section can be above 40%.[13]

Pressing is the most efficient method of de-watering the sheet as only mechanical action is required. Press felts historically were made from wool. However, today they are nearly 100% synthetic. They are made up of a polyamide woven fabric with thick batt applied in a specific design to maximise water absorption.

Presses can be single or double felted. A single felted press has a felt on one side and a smooth roll on the other. A double felted press has both sides of the sheet in contact with a press felt. Single felted nips are useful when mated against a smooth roll (usually in the top position), which adds a two-sidednessâ€”making the top side appear smoother than the bottom. Double felted nips impart roughness on both sides of the sheet.  Double felted presses are desirable for the first press section of heavy paperboard.

Simple press rolls can be rolls with grooved or blind drilled surface. More advanced press rolls are suction rolls. These are rolls with perforated shell and cover. The shell made of metal material such as bronze stainless steel is covered with rubber or a synthetic material. Both shell and cover are drilled throughout the surface. A stationary suction box is fitted in the core of the suction roll to support the shell being pressed. End face mechanical seals are used for the interface between the inside surface of the shell and the suction box. For the smooth rolls, they are typically made of granite rolls.[14] The granite rolls can be up to 30-foot (9.1 m) long and 6 feet (1.8 m) in diameter.[15]

Conventional roll presses are configured with one of the press rolls is in a fixed position, with a mating roll being loaded against this fixed roll. The felts run through the nips of the press rolls and continues around a felt run, normally consisting of several felt rolls. During the dwell time in the nip, the moisture from the sheet is transferred to the press felt. When the press felt exits the nip and continues around, a vacuum box known as an Uhle Box applies vacuum (normally -60 kPa) to the press felt to remove the moisture so that when the felt returns to the nip on the next cycle, it does not add moisture to the sheet.

Some grades of paper use suction pick up rolls that use vacuum to transfer the sheet from the couch to a lead in felt on the first press or between press sections.  Pickup roll presses normally have a vacuum box that has two vacuum zones (low vacuum and high vacuum). These rolls have a large number of drilled holes in the cover to allow the vacuum to pass from the stationary vacuum box through the rotating roll covering. The low vacuum zone picks up the sheet and transfers, while the high vacuum zone attempts to remove moisture. Unfortunately, at high enough speed centrifugal force flings out vacuumed water, making this less effective for dewatering. Pickup presses also have standard felt runs with Uhle boxes. However, pickup press design is quite different, as air movement is important for the pickup and dewatering facets of its role.

Crown Controlled Rolls (also known as CC Rolls) are usually the mating roll in a press arrangement. They have hydraulic cylinders in the press rolls that ensure that the roll does not bow. The cylinders connect to a shoe or multiple shoes to keep the crown on the roll flat, to counteract the natural "bend" in the roll shape due to applying load to the edges.

Extended Nip Presses (or ENP) are a relatively modern alternative to conventional roll presses. The top roll is usually a standard roll, while the bottom roll is actually a large CC roll with an extended shoe curved to the shape of the top roll, surrounded by a rotating rubber belt rather than a standard roll cover. The goal of the ENP is to extend the dwell time of the sheet between the two rolls thereby maximising the de-watering. Compared to  a standard roll press that achieves up to 35% solids after pressing, an ENP brings this up to 45% and higherâ€”delivering significant steam savings or speed increases.  ENPs densify the sheet, thus increasing tensile strength and some other physical properties.

The dryer section of the paper machine, as its name suggests, dries the paper by way of a series of internally steam-heated cylinders that evaporate the moisture. Steam pressures may range up to 160 psig. Steam enters the end of the dryer head (cylinder cap) through a steam joint and condensate exits through a siphon that goes from the internal shell to a centre pipe.  From the centre pipe the condensate exits through a joint on the dryer head.  Wide machines require multiple siphons.  In faster machines, centrifugal force holds the condensate layer still against the shell and turbulence generating bars are typically used to agitate the condensate layer and improve heat transfer.[13]

The sheet is usually held against the dryers by long felt loops on the top and bottom of each dryer section.  The felts greatly improve heat transfer.  Dryer felts are made of coarse thread and have a very open weave that is almost see through,  It is common to have the first bottom dryer section unfelted to dump broke on the basement floor during sheet breaks or when threading the sheet.

Paper dryers are typically arranged in groups called sections  so that they can be run at a progressively slightly slower speed to compensate for sheet shrinkage as the paper dries. Some grades of paper may also stretch as they run through the machine, requiring increasing speed between sections.  The gaps between sections are called draws.

The drying sections are usually enclosed to conserve heat.  Heated air is usually supplied to the pockets where the sheet breaks contact with the driers.  This increases the rate of drying. The pocket ventilating tubes have slots along their entire length that face into the pocket.  The dryer hoods are usually exhausted with a series of roof mounted hood exhausts fans down the dryer section.

Additional sizing agents, including resins, glue, or starch, can be added to the web to alter its characteristics. Sizing improves the paper's water resistance, decreases its ability to fuzz, reduces abrasiveness, and improves its printing properties and surface bond strength.  These may be applied at the wet (internal sizing) or on the dry end (surface sizing), or both. At the dry end sizing is usually applied with a size press. The size press may be a roll applicator (flooded nip) or Nozzle applicator.   It is usually placed before the last dryer section.  Some paper machines also make use of a 'coater' to apply a coating of fillers such as calcium carbonate or china clay usually suspended in a binder of cooked starch and styrene-butadiene latex.  Coating produces a very smooth, bright surface with the highest printing qualities.

A calender consists of two or more rolls, where pressure is applied to the passing paper. Calenders are used to make the paper surface extra smooth and glossy. It also gives it a more uniform thickness. The pressure applied to the web by the rollers determines the finish of the paper.

After calendering, the web has a moisture content of about 6% (depending on the furnish). The paper is wound onto metal spools using a large cylinder called a reel drum. Constant nip pressure is maintained between the reel drum and the spool, allowing the resulting friction to spin the spool. Paper runs over the top of the reel drum and is wound onto the spool to create a master roll.

To be able to keep the paper machine running continuously, the reel must be able to quickly switch from winding a finished roll to an empty spool without stopping the flow of paper. To accomplish this, each reel section will have two or more spools rotating through the process. Using an overhead crane, empty spools will be loaded onto two primary arms above the reel drum. When the master roll reaches its maximum diameter, the arms will lower the new spool into contact with the reel drum and a machine behind the drum will run a tape along the moving sheet of paper, swiftly tearing it and attaching incoming paper onto the new spool. The spool is then lowered onto the secondary arms, which steadily guide the spool away from the reel drum as the diameter of paper on the spool increases.

The roll hardness should be checked, obtained and adjusted accordingly to insure that the roll hardness is within the acceptable range for the product.

Reels of paper wound up at the end of the drying process are the full trimmed width, minus shrinkage from drying, of the web leaving the wire.  In the winder section reels of paper are slit into smaller rolls of a width and roll diameter range specified by a customer order. To accomplish this the reel is placed on an unwind stand and the distances between the slitters (sharp cutting wheels), are adjusted to the specified widths for the orders.  The wider is run until the desired roll diameter is reached and the rolls are labeled according to size and order before being sent to shipping or the warehouse.  A reel usually has sufficient diameter to make two or more sets of rolls.

broke: waste paper, either made during a sheet break or trimmings.  It is gathered up and put in a repulper for recycling back into the process.

consistency: the percent dry fibre in a pulp slurry.

couch: French meaning to lie down.  Following the couch roll the sheet is lifted off the wire and transferred into the press section.

dandy roll: a mesh covered hollow roll that rides on top of the Fourdrinier. It breaks up fibre clumps to improve the sheet formation and can also be used to make an imprint, as with laid paper. See also watermark.

fan pump: the large pump that circulates white water from the white water chest to the headbox.  The pump is a special low pulse design that minimizes the effect of vane pulses which would cause uneven basis weight of paper in the machine direction known as barring. The flow from the fan pump may go through screens and cleaners, if used.  On large paper machines fan pumps may be rated in tens of thousands of gallons per minute.

felt: a loop of fabric or synthetic material that goes between press rolls and serves as a place to receive the pressed out water.  Felts also support the wet paper web and guide it through the press section. Felts are also used in the dryer section to keep the sheet in close contact with the dryers and increase heat transfer.

filler: a finely divided substance added to paper in the forming process.  Fillers improve print quality, brightness and opacity.  The most common fillers are clay and calcium carbonate. Titanium dioxide is a filler but also improves brightness and opacity.  Use of calcium carbonate filler is the process called alkaline sizing and uses different chemistry than acid sizing.  Alkaline sized paper has superior ageing properties.

formation: the degree of uniformity of fiber distribution in finished paper, which is easily seen by holding paper up to the light.

headbox: the pressure chamber where turbulence is applied to break up fibre clumps in the slurry.  The main job of the headbox is to distribute the fiber slurry uniformly across the wire.

nip: the contact area where two opposing rolls meet, such as in a press or calender.

pH: the degree of acidity or alkalinity of a solution. Alkaline paper has a very long life.  Acid paper deteriorates over time, which caused libraries to either take conservation measures or replace many older books.

size: a chemical (formerly rosin derived but now a different chemical) or starch, applied to paper to retard the rate of water penetration.  Sizing prevents bleeding of ink during printing, improving the sharpness of printing.

slice: the adjustable rectangular orifice, usually at the bottom of the headbox, through which the whitewater jet discharges onto the wire.  The slice opening and water pressure together determine the amount and velocity of whitewater flow through the slice.  The slice usually has some form of adjustment mechanism to even out the paper weight profile across the machine (CD profile), although a newer methods is to inject water into the whitewater across the headbox slice area, thereby using localized consistency to control CD weight profile.

stock: a pulp slurry that has been processed in the stock preparation area with necessary additives, refining and pH adjustment and ready for making paper

web: the continuous flow of un-dried fibre from the couch roll down the paper machine

white water: filtrate from the drainage table.  The white water from the table is usually stored in a white water chest from which it is pumped by the fan pump to the headbox.

wire: the woven mesh fabric loop that is used for draining the pulp slurry from the headbox. Until the 1970s bronze wires were used but now they are woven from coarse mono-filament synthetics similar to fishing line but very stiff.

Stainless steels are used extensively in the Pulp and Paper industry[16] for two primary reasons, to avoid iron contamination of the product and their corrosion resistance to the various chemicals used in the paper making process. Type 316 stainless steel is a common material used in paper machines.


what does the water at the 9 11 memorial represent

In January 2004, Reflecting Absence, by architect Michael Arad and landscape architect Peter Walker, was selected from 5,201 entries from 63 countries as the winner of the LMDC's design competition. Two 1-acre (4,000Â m2) pools with the largest man-made waterfalls in the United States comprise the footprints of the Twin Towers, symbolizing the loss of life and the physical void left by the attacks. The waterfalls are intended to mute the sounds of the city, making the site a contemplative sanctuary. Landscape architect Peter Walker planted many parts of the memorial with white oaks.[43] More than 400 swamp white oak trees fill the Memorial plaza, enhancing the site's reflective nature.[44]

National September 11 Memorial & Museum

The National September 11 Memorial & Museum (also known as the 9/11 Memorial & Museum) is a memorial and museum in New York City commemorating the September 11, 2001 attacks, which killed 2,977 people, and the 1993 World Trade Center bombing, which killed six.[4] The memorial is located at the World Trade Center site, the former location of the Twin Towers that were destroyed during the September 11 attacks. It is operated by a non-profit institution whose mission is to raise funds for, program, and operate the memorial and museum at the World Trade Center site.

A memorial was planned in the immediate aftermath of the attacks and destruction of the World Trade Center for the victims and those involved in rescue and recovery operations.[5] The winner of the World Trade Center Site Memorial Competition was Israeli architect Michael Arad of Handel Architects, a New York- and San Francisco-based firm. Arad worked with landscape-architecture firm Peter Walker and Partners on the design, creating a forest of swamp white oak trees with two square reflecting pools in the center marking where the Twin Towers stood.[6]
In August 2006, the World Trade Center Memorial Foundation and the Port Authority of New York and New Jersey began heavy construction on the memorial and museum.[7] The design is consistent with the original master plan by Daniel Libeskind, which called for the memorial to be 30 feet (9.1 m) below street level—originally 70 feet (21 m)—in a plaza, and was the only finalist to disregard Libeskind's requirement that the buildings overhang the footprints of the Twin Towers. The World Trade Center Memorial Foundation was renamed the National September 11 Memorial & Museum in 2007.[8]

A dedication ceremony commemorating the tenth anniversary of the attacks was held at the memorial on September 11, 2011, and it opened to the public the following day. The museum was dedicated on May 15, 2014, with remarks from Michael Bloomberg and President Barack Obama. The museum opened to the public on May 21.

In September 2007 the Memorial & Museum began a four-month national-awareness tour of 25 cities in 25 states, and thousands participated in tour activities.[9] The tour began at Finlay Park in Columbia, South Carolina, ending at Steinbrenner Field in Tampa, Florida. Highlights included an exhibition of photographs, artifacts from the site and a film with firsthand accounts from individuals who had directly experienced the attacks. At the opening ceremony in South Carolina, the students of White Knoll Middle School (who raised over $500,000 in 2001 for a new truck for the New York City Fire Department) were honored and retired New York City police officer Marcelo Pevida presented the city with an American flag which had flown over Ground Zero.[10] The main attractions of the 2007 national tour were steel beams, later used in the construction of the memorial, for visitors to sign.[11]

The National September 11 Memorial & Museum conducts a "cobblestone campaign", in which a contributor may sponsor a cobblestone which will line the Memorial plaza. Donors are recognized on the Memorial's website.[12] Donors are able to locate their cobblestone by entering their name at a kiosk on the Memorial plaza.[13] In 2008 the Memorial conducted two holiday cobblestone campaigns: the first for Father's Day, and the second for the December holiday season.[14][15]

On September 9, 2011, Secretary Shaun Donovan of the United States Department of Housing and Urban Development said that the department had given $329 million to the National September 11 Memorial & Museum through HUD's Community Development Block Grant program.[16] According to CNN, the Port Authority of New York and New Jersey dropped its claim that the 9/11 Memorial & Museum owed it $300 million in construction costs in return for "financial oversight of the museum and memorial".[17]

Senator Daniel Inouye of Hawaii sponsored S.1537, the National September 11 Memorial and Museum Act of 2011, which would provide $20Â million in federal funds annually toward the Memorial's operating budget (about one-third of its total budget). The legislation was presented to the U.S. Senate Committee on Energy and Natural Resources on October 19, 2011.[18] In return for federal funding S.1537 would authorize the Secretary of the Interior to accept the donation by the memorial's board of directors of title to the National September 11 Memorial, contingent on agreement by the board, the governors of New York and New Jersey, the Mayor of New York and the Secretary of the Interior. On October 19, 2011 William D. Shaddox of the National Park Service voiced concerns to the Senate Committee on Energy and Natural Resources about the agency's ability to provide the funds required by S.1537, testifying that NPS ownership of a property over which it would not have operational and administrative control (as stipulated by S.1537) was unprecedented.[19]

National September 11 Memorial & Museum at the World Trade Center: About Us, Mission Statements

Formerly the World Trade Center Memorial Foundation, the National September 11 Memorial & Museum was formed as a 501(c)(3) non-profit corporation to raise funds and manage  the memorial's planning and construction. Its board of directors met for the first time on January 4, 2005, and it reached its first-phase capital-fundraising goal ($350Â million) in April 2008. This money and additional funds raised will be used to build the memorial and museum and endow the museum.

In 2003, the Lower Manhattan Development Corporation launched the World Trade Center Site Memorial Competition, an international competition to design a memorial at the World Trade Center site to commemorate the lives lost on 9/11. Individuals and teams from around the world submitted design proposals.[20] On November 19, 2003, the thirteen-member jury selected eight finalists.[20] Reflecting Absence, designed by Michael Arad and Peter Walker, was chosen as the winning design on January 6, 2004.[21] It consists of a field of trees interrupted by two large, recessed pools, the footprints of the Twin Towers. The deciduous trees (swamp white oaks)[22] are arranged in rows and form informal clusters, clearings and groves. The park is at street level, above the Memorial Museum.[23] The names of the victims of the attacks (including those from the Pentagon, American Airlines Flight 77, United Airlines Flight 93, and the 1993 World Trade Center bombing) are inscribed on the parapets surrounding the waterfalls[24] in an arrangement of "meaningful adjacencies".[25] A portion of the slurry wall originally designed to hold back the Hudson River, about half of what Daniel Libeskind originally wanted to preserve,[26] is maintained in the museum. On January 14, 2004, the final design for the World Trade Center site memorial was unveiled at a press conference in Federal Hall National Memorial.[20]

As mandated by the Lower Manhattan Development Corporation (LMDC), the World Trade Center Memorial Foundation owns, operates and finances the Reflecting Absence Memorial and the Museum. John C. Whitehead, chair of the LMDC and the foundation, announced his resignation in May 2006 and was replaced at the LMDC by former president Kevin Rampe. New York City Mayor Michael Bloomberg replaced Whitehead as chair of the National September 11 Memorial & Museum. Foundation executive committee chair Thomas S. Johnson said on May 9, 2006:

The decision was made to not actively pursue new fund-raising efforts until complete clarity can be achieved with respect to the design and costs of the project. Cost concerns emerged publicly last week with the disclosure of an estimate by the construction manager, Lend Lease Group, that the memorial and museum would cost $672 million and that it would take a total of at least $973 million to fully develop the memorial setting with a cooling plant, roadways, sidewalks, utilities and stabilized foundation walls. An estimate earlier this year put the cost of the memorial and memorial museum at $494 million.[27]

On May 26, 2006, Gretchen Dykstra resigned as president and chief executive officer of the World Trade Center Foundation.[28] Joseph C. Daniels was appointed as president and CEO in October 2006.[29] The memorial projects were toned down, and the budget was cut to $530Â million.[30] Construction of the memorial began in August 2006 and, despite delays, the National September 11 Memorial & Museum was confident that it would be completed by September 11, 2011.[31]

On March 13, 2006, construction workers arrived at the WTC site to begin work on the Reflecting Absence design. Some relatives of the victims and other concerned citizens gathered to protest the new memorial that day, saying that it should be built above ground. The president of the memorial foundation said that family members were consulted and formed a consensus in favor of the design, and work would continue as planned.[32][33]
In May, estimated construction costs for the Memorial were reported to have risen to over $1 billion.[34] Mayor Michael Bloomberg said, "There's just not an unlimited amount of money that we can spend on a memorial. Any figure higher than $500 million would be inappropriate."[35]

In 2006, at the request of Bloomberg and Governor George Pataki, builder Frank Sciame performed a month-long analysis which included input from victims' families, the lower Manhattan business and residential communities, architects and members of the memorial-competition jury. The analysis recommended design changes which kept the memorial and museum within a $500Â million budget.[36][37]

In July 2008, the Survivors' Staircase was lowered to bedrock, making it the first artifact to be moved into the museum. By the end of August, the footings and foundations were completed. On September 2 construction workers raised the 7,700-pound (3,500 kg) first column for the memorial, near the footprint of the North Tower.[38] By then, about 70 percent of the construction contracts were awarded or ready to award. A total of 9,100 short tons (8,300 t) of steel were installed at the memorial site.[39] By April 2010 the reflecting pools were fully framed in steel, and 85 percent of the concrete had been poured. By April 22, workers had begun installation of the granite coating for the reflecting pools. By June the North Pool's granite coating was completed, and workers had begun granite installation in the South Pool. In July, the first soil shipments arrived at the site, and in August workers began planting trees on the memorial plaza. The swamp white oaks can reach 60 to 80 feet (18 to 24 m) at maturity, live from 300 to 350 years, and their autumn leaves are gold-colored. The "Survivor Tree" is a callery pear which survived the devastation and was kept for replanting.[40] In September, workers reinstalled two tridents salvaged from the Twin Towers.

In November 2010, workers began testing the North Pool waterfall, and construction progressed through early 2011. In March installation of glass panels on the museum pavilion's faÃ§ade began, and in May workers began testing the South Pool waterfall. Most of the memorial was finished in time for the 10th anniversary of the terrorist attacks, with the museum planned for completion one year later. By September 2, 243 trees were planted at the site and eight more were planted in the days before the memorial opened. By then, both pools were completed and the waterfalls were tested daily.

On September 12, 2011, one day after the 10th anniversary of the September 11 terrorist attacks, the memorial opened to the public with a lengthy set of rules and regulations approved by the foundation's board of directors. The period from September 11, 2011 to May 25, 2014 was known as the "interim operating period", when the memorial was surrounded by construction of neighboring World Trade Center projects; the fence was taken down on May 25, 2014.[41] Three months after its opening, the memorial had been visited by over a million people.[42]

Pedestrian simulations tested the memorial's design. The pedestrian-modeling program Legion was used to simulate visitor utilization of the space, and its design was tweaked to prevent bottlenecks.[45] The fountain was engineered by Delta Fountains.[46]

The names of 2,983 victims are inscribed on 152 bronze parapets on the memorial pools:[47] 2,977 killed in the September 11 attacks and six killed in the 1993 World Trade Center bombing. The names are arranged according to an algorithm, creating "meaningful adjacencies" based on relationshipsâ€”proximity at the time of the attacks, company or organization affiliations (for those working at the World Trade Center or the Pentagon) and in response to about 1,200 requests from family members. Software by Local Projects[48] implemented the arrangement.[49]

The names of the employees and visitors in the North Tower (WTC 1), the passengers and crew of American Airlines Flight 11 (which struck the North Tower), and the employees and a visitor of the 1993 World Trade Center bombing are around the perimeter of the North Pool. The names of the employees and visitors in the South Tower (WTC 2), the passengers and crew of United Airlines Flight 175 (which struck the South Tower), the employees, visitors, and bystanders in the immediate vicinity of the North and South Towers, the first responders who died during rescue operations, the passengers and crew of United Airlines Flight 93 (which crashed near Shanksville, Pennsylvania) and American Airlines Flight 77 (which struck the Pentagon), and the employees at the Pentagon are around the perimeter of the South Pool.[50] Company names are not included, but company employees and visitors are listed together. Passengers on the four flights are listed under their flight numbers, and first responders with their units.

The process for arranging the names was finalized in a 2006 agreement, replacing an earlier plan to arrange the names randomly. According to Edith Lutnick (executive director of the Cantor Fitzgerald Relief Fund), "Your loved ones' names are surrounded by the names of those they sat with, those they worked with, those they lived with and, very possibly, those they died with."[51]

The six adult victims of the 1993 bombing are memorialized on Panel N-73 at the North Pool.[52] The phrase "and her unborn child" follows the names of ten pregnant women who died on 9/11 and one who died in the 1993 attack.[53]

A callery pear tree recovered from the rubble at the World Trade Center site in October 2001 was later called the "Survivor Tree".[54][55] When the 8-foot (2.4 m)-tall tree was recovered,[56] it was badly burned and had one living branch.[54] The tree had been planted during the 1970s near buildings four and five, in the vicinity of Church Street.[57] Then-Memorial president Joe Daniels described it as "a key element of the memorial plaza's landscape".[54]

In November 2001, the tree was moved by the New York City Department of Parks and Recreation to the Arthur Ross Nursery in Van Cortlandt Park in the Bronx for care. It was then replanted in the Bronx on November 11, 2001.[58] The tree was not expected to survive, but it showed signs of new growth the following spring.[55] Although the memorial planning team intended to include the Survivor Tree, its permanent location was unknown at the time.[58]

Still under the care of the Bronx nursery, the tree was replanted without significant damage in March 2010 after it was uprooted by a storm.[57] After the replanting, Mayor Michael Bloomberg said: "Again, we and the tree refused to throw in the towel. We replanted the tree, and it bounced back immediately."[54]

The Survivor Tree has become a symbol of hope and rebirth; according to Arthur Ross Nursery manager Richie Cabo, "It represents all of us."[55] In an August 29, 2011 Port Authority press release (after Hurricane Irene), Daniels said: "True to its name, the Survivor Tree is standing tall at the Memorial."[59] Keating Crown (a survivor of the attacks) said, "It reminds us all of the capacity of the human spirit to persevere."[55] A Place of Remembrance: Official Book of the National September 11 Memorial describes the tree as "a reminder of the thousands of survivors who persevered after the attacks".[60]

In December 2010, the tree, then 30 feet (9.1Â m) tall,[55] was returned to the World Trade Center site in a ceremony attended by Bloomberg, city officials[56] (including Parks and Recreation Commissioner Adrian Benepe and Port Authority executive director Chris Ward), survivors and rescue and recovery workers.[55][56] Although the tree is a prominent part of the memorial,[61] six other "survivor trees" have been planted near New York City Hall and the Manhattan end of the Brooklyn Bridge. Of these survivor trees, three are callery pears and three are little-leaf lindens.[62]

In May 2018, plans were revealed for a path through a "memorial glade" at the National September 11 Memorial. The path will honor first responders who later got sick or died after inhaling toxins at the World Trade Center site. According to 9/11 Memorial & Museum president Alice Greenwald and former Daily Show host Jon Stewart, the path will be located on the southwest side of the memorial plaza, at the approximate site of a temporary ramp that first responders used during the cleanup effort. The path will include six large battered stones that, in the words of Michael Arad, "appear to jut up and out of the plaza as if violently displaced, and convey strength and resistance". Several pieces of debris from the original World Trade Center will also be placed along the path.[63][64]

Although victims'-family groups agreed that names would be grouped by workplace or other affiliation, NYPD cadet Mohammad Salman Hamdani was not included with the other first responders or the other victims whose remains were found in the wreckage of the North Tower. His name appears on the memorial's panel 66 for World Trade Center victims (next to a blank space along the South Tower perimeter), with those who did not fit into the groups created by the memorial committee or who had a loose connection to the World Trade Center. Hamdani's mother, Talat, has campaigned for the Memorial to acknowledge her son as a police cadet and first responder.[65] Hamdani received a full police-department funeral after his body was found (months after the attacks), and the street on which he lived was renamed in his honor.[66]

Although the memorial's brochures were initially translated into at least ten languages, these languages did not include Arabic.[67] The American-Arab Anti-Discrimination Committee (ADC) questioned this decision in letters to memorial directors, and ADC director of communications and advocacy Raed Jarrar said: "Our fear is that there is a political intention behind the exclusion".[67] A memorial representative told the New York Post, "As Arabic-speaking visitors currently represent our 25th-largest group, Arabic translations are not yet among the initial foreign-language editions."[67]

In 2015, the American-Arab Anti-Discrimination Committee made an official complaint with the U.S. Department of Housing and Urban Development, which had given hundreds of millions of dollars in grants to the September 11 Memorial through block grants to the Lower Manhattan Development Corporation. The committee stated that the Memorial's decision to not publish Arabic-language brochures violated HUD's Limited English Proficiency rules for grantees. In December 2017, the ADC announced that the Memorial had signed a settlement agreement whereby its commemorative guide would be translated into Arabic and made available.[68]

The September 11 Museum was dedicated on May 15, 2014,[69][70][71] and opened to the public on May 21.[3][72] Its collection includes more than 40,000 images, 14,000 artifacts, more than 3,500 oral recordings, and over 500 hours of video.[3]

The underground museum has artifacts from September 11, 2001, including steel from the Twin Towers (such as the Last Column, the last piece of steel to leave Ground Zero in May 2002).

In December 2011, museum construction halted temporarily due to disputes between the Port Authority of New York and New Jersey and the National September 11 Memorial and Museum Foundation over responsibility for infrastructure costs.[73][74] On March 13, 2012, talks on the issue began,[75][76] and construction resumed on September 10, 2012.[77][78] After a number of false opening reports, it was announced that the museum would open to the public on May 21, 2014.[79][80][81]

The museum was dedicated on May 15, 2014.[69][70][71] In attendance were a range of dignitaries, from President Barack Obama, former President Bill Clinton, former Secretary of State Hillary Clinton and New York Governor Andrew Cuomo to former mayors David Dinkins, Rudy Giuliani and Michael Bloomberg and current mayor Bill de Blasio. During the hour-long ceremony LaChanze sang "Amazing Grace", which she dedicated to her husband (who was killed in the World Trade Center that day).[2] During the five days between its dedication and the public opening, over 42,000 first responders and family members of 9/11 victims visited the museum.[82]

An opening ceremony for the museum was held on May 21,[3][72] during which twenty-four police officers and firefighters unfurled the restored 30-foot (9.1Â m) national 9/11 flag before it was brought into the museum for permanent display.[83][84][85] The gates surrounding the museum were then taken down, marking their first removal since the attacks.[85] Opening-day tickets quickly sold out.[86] Despite the museum's design (to evoke memories without additional distress),[87] counselors were available during its opening due to the large number of visitors.[82]

Designed by Davis Brody Bond, the museum is about 70 feet (21 m) below ground and accessible through a pavilion designed by Snøhetta.[88] The National September 11 Memorial Museum encloses 110,000 square feet (10,000 m2) of publicly accessible space.[89] The pavilion has a deconstructivist design, resembling a partially collapsed building (mirroring the attacks), and houses two tridents from the Twin Towers. One of the museum's walls is an exposed side of the slurry wall retaining the Hudson River, which remained intact during (and after) September 11.[90][91]

Other Ground Zero artifacts include wrecked emergency vehicles (including a fire engine deformed from the collapse), pieces of metal from all seven World Trade Center buildings, recordings of survivors and first responders (including 911 phone calls), pictures of all victims, photographs from the wreckage and other media detailing the destruction (including the crashes, collapse, fires, those who jumped and the cleanup).[92] The museum is designed to evoke memories without additional distress, particularly to first responders and the families of victims.[87]

The Huffington Post wrote that "walking through the museum is like being transported back to the turmoil, destruction and anguish of 9/11. Exhibits express the disbelief and heartache of New York and the nation."[93]

The World Trade Center site was once part of Little Syria, the center of Arab life in the United States since the 1880s. The cornerstone of St. Joseph's Lebanese Maronite Church was found under the rubble, next to St. Nicholas Greek Orthodox Church at 157 Cedar Street.[94] Local historians and preservationists have requested that the National September 11 Museum include a reference to this history in the Museum's permanent exhibit to "help the thousands of tourists who visit the site to understand that Arab-Americans have played a patriotic role in the country's history". According to the New York Daily News, a museum spokesperson said that its "curators are not planning to include information about the area's Arab-American history in the museum's permanent collection."[95]  "Save Washington Street" advocates had approached the museum after hearing there would be a display about the construction of the World Trade Center site and the demolition of Radio Row, the electronic district cleared to make way for the towers.[96] They have also articulated the need for recalling the multiethnic character of "Little Syria", along with the Downtown Community House that served it, as extremely important for the historical memory of New York City and of the United States.[97]

General admission tickets to the museum are $24, a price which has raised concerns. Michael Bloomberg agreed, encouraging people to "write your congressman" for more federal funding.[98][99][100]

When the museum opened to victim families and first responders on May 15, 2014, anger by some that it was profiting from souvenirs considered in poor taste was widely covered.[101][102][103][104][105][106] Souvenir proceeds would fund the museum and memorial.[107][108][109] On May 29, 2014, a U.S.-shaped cheese platter was among items removed for sale, and it was announced that all items sold would be reviewed by victim families for suitability.[110]

Families were further angered after a May 20, 2014 black-tie, VIP cocktail party for donors at the museum. Among the 60 attendees were former mayor Michael Bloomberg and representatives of Condé Nast. Family members objected to a party near unidentified remains; the sister of victim Robert Shay, Jr. tweeted, "Did you enjoy having drinks on top of my brother's grave last night?" Shay and dozens of other visitors were angered that first responders were turned away from the museum the previous day while staff prepared for the party. She said, "I am outraged that I can't visit my brother's final resting place without an appointment but people like Mike Bloomberg can wine and dine there whenever they want. This memorial and museum is sacred ground and last night it was desecrated." A retired FDNY fire marshal said, "You don't have cocktail parties at a cemetery."[109][111][112] A mid-2014 proposal to open a Danny Meyer cafe in the museum's atrium was criticized.[113][114][115]

In an early-morning ceremony on May 10, 2014, the long-unidentified remains of 1,115 victims were transferred from the city medical examiner to Ground Zero, where they would be placed in a space in the bedrock 70 feet (21Â m) below ground as part of the 9/11 Memorial Museum. Reaction from the victims' families to the move was divided, with some supporting the decision and others calling the location inappropriate. Among the latter was FDNY Lt. James McCaffrey, the brother-in-law of 9/11 victim and firefighter Orio Palmer, who called a ground-level tomb a more dignified location: "The decision to put the human remains of the 9/11 dead in this basement is inherently disrespectful and totally offensive." McCaffrey said that the remains deserved a prominence equal to that of the Memorial's trees and pools, and that the ceremony was held early in the morning because of opposition to the decision.[116]

Two centers were proposed and withdrawn from the World Trade Center Memorial plan in 2005:

Plans called for the Freedom Center to share space with the Drawing Center in a building known as the Cultural Center. Of the dispute over the proposed centers, one New York Times editorial stated not only that the IFC's opponents make trivial and unconvincing suggestions that both the IFC and the "cultural component" of architect Daniel Libeskind's plans would somehow diminish the scope of the Memorial Museum, but also that the proposal for reducing the size of one of the centers had failed to consider the emotional impact of the space.[119]

Panorama of North Pool

North Pool with construction of the museum, September 2011

South Pool with construction of the museum, April 2012. Tower 3, Tower 4, and Tower 7 are in the background.

Remnant of the original Slurry Wall in the Bathtub at the museum

Remnant of the Survivors' Staircase, or Vesey Street Stairs

White rose at the memorial

North Pool at night; panel N-76, showing the name ofBerry Berenson

South Pool at night; panel S-66, showing the name of Bill Biggart

South Pool panel S-29, paying tribute to the Jersey City Fire Department

South Pool at night; panel S-17, showing the name of Peter J. Ganci, Jr.

South Pool panel S-68, showing the name of Todd Beamer

South Pool panel S-67, showing the name of Mark Bingham

South Pool panel S-67, showing the name of Jeremy Glick

South Pool panel S-68, showing the name of Tom Burnett

North Pool panel N-73, with the names of the victims of the 1993 bombing

In addition to the one at Ground Zero, a number of other memorials have been built by communities across the United States. Many are built around remnants of steel from the Twin Towers which have been donated by a Port Authority of New York and New Jersey program; over 1,000 pieces of World Trade Center steel have been distributed.[120]