LONDON (Reuters) - A U.S. and British library plan to reproduce online all 75 editions of William Shakespeare's plays printed in the quarto format before the year 1641.

The Bodleian Library in Oxford and Folger Shakespeare Library in Washington DC have joined forces to download their collections, building on the work of the British Library which digitized its collection of quarto editions in 2004.

In the absence of surviving manuscripts, the quartos -- Shakespeare's earliest printed editions -- offer the closest known evidence of what Shakespeare might actually have written, and what appeared on the early modern English stage.

The project is designed to make all of the quartos, many of which are only accessible to scholars, available to the wider public.

The process of downloading the quartos will begin next month and take a year to complete.

Online visitors will be able to compare images side-by-side, lay one facsimile on top of the other, search plays and mark and tag the texts.

As well as highlighting more minor differences between copies of the same quarto, the digital database will also make it easier to study the often wide discrepancies between quartos, including some of Shakespeare's most famous lines.

"There will be countless new ways for scholars, teachers, and students to examine the quarto texts, particularly of 'Hamlet'," said Folger director Gail Kern Paster.

"You find out all sorts of things -- about how the copies went through the press, and also about the printing process," she added.

Shakespeare wrote at least 37 plays and collaborated on several more between about 1590 and 1613. He died in 1616.

(Reporting by Mike Collett-White, editing by Paul Casciato)

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