In the weeks following the Beinecke Rare Book and Manuscript Library’s 50th anniversary, the library has another cause for celebration — a new and extensive collection of one-of-a-kind original medieval manuscripts.

After a presentation ceremony on Oct. 19, the Beinecke became home to 51 Middle English manuscripts, including three manuscripts of Chaucer’s “Canterbury Tales,” several original prayer rolls and a Wycliffite Bible. The collection — which comes as a long-term loan from Toshiyuki Takamiya, a retired professor of medieval English literature at the University of Keio in Japan — also includes an assortment of chronicles and histories, in addition to religious and mystical writings.

“It’s a real coup for Yale, making Beinecke the largest collection of Middle English manuscripts outside of Britain,” said Ian Cornelius, an English assistant professor at Yale.

Due to the frequency and magnitude of earthquakes in Japan, Cornelius said, Takamiya decided that the Beinecke would be an ideal repository for his private collection of manuscripts. Cornelius added that Yale’s reputation for being a strong center for medieval studies also appealed to Takamiya.

According to Raymond Clemens, curator of the Early Books and Manuscripts collection in the Beinecke, the loan is open-ended. Though Takamiya retains official ownership of the collection, the Beinecke will hold the collection in its building until Takamiya asks for its return.

Before the new loan, Yale did not possess any originals of Chaucer’s works. Now, with several copies of “Canterbury Tales” and other smaller documents signed by the author, the University holds more Chaucer works than any other institution in the country, Clemens said.

Among the Chaucer works now in the Beinecke’s possession are the Devonshire “Canterbury Tales” manuscript — a richly illuminated, expensive edition of the complete tales — and a smaller edition that Clemens said contains slightly racier stories, dubbed “the English gentleman’s book” by Takamiya.

English professor Ardis Butterfield said that of the 83 original “Canterbury Tales” manuscripts in the world, roughly 57 are complete. The ordering of the stories also varies from manuscript to manuscript.

“Looking at all the different groups and types of manuscripts that contain the ‘Canterbury Tales’ is one way of puzzling through some of the ways in which [Chaucer] put the whole collection together,” Butterfield said. “It’s very much a work that he was revising and rethinking.”

Takamiya’s loan to the Beinecke also includes a scientific treatise written by Chaucer. Though many people do not think of Chaucer as a scientific writer, Cornelius said, his scientific work was widely copied in the 15th century.

The new collection can also be used to compare historical changes in language and religion — for example, it boasts a manuscript of William Langland’s poem “Piers Plowman” from around 1550, which can be compared with Beinecke’s print editions of the poem from 1550, and also an earlier manuscript of the poem, to understand the ways in which the text has been updated.

“There’s been a lot of work on the print copy from 1550 about the extent to which it’s a Protestant version of this medieval Catholic text,” Cornelius said. “Some of those same questions could now be posed to the manuscript copy.”

Butterfield said she believes that research at Yale will benefit from the new collection. One of the major projects at Yale with regard to Chaucer manuscripts is the study of ink colors, she said, as color changes can indicate specific scribes or later alterations that were made in the text.

Students at Yale said they are excited by the Takamiya collection. Julia Mattison ’14 said that her senior thesis, which will likely examine 14th- and 15th-century book-binding practices, could benefit from many of the manuscripts in the collection.

“I think that’s the exciting thing about manuscripts — even after all this time, they still have a huge number of secrets,” Butterfield said.

Other manuscripts in the collection include a prayer roll composed in Latin and English, Nicholas Love’s “Mirror of the Blessed Life of Jesus Christ,” Walter Hilton’s “Scale of the Perfection” and a fragment of John Lydgate’s “Fall of Princes.”

Correction: Nov. 6

A previous version of this article stated that Julia Mattison ’14 will examine almost all of the collection’s manuscripts for her senior thesis. In fact, Mattison said she may examine some of the manuscripts for her senior thesis, which is not yet finalized.