Checking out that DiVinci book

Like museums, libraries are sometimes put in the ironic position of having to keep their holdings away from the public, in order to preserve them for the public. As contradictory as the policy may seem, libraries can't just sign out a Leonardo Codex to anyone with a borrower's card, and thanks to the Web, they don't have to. Like museums, libraries can now place accurate and interactive facsimiles of their collection online for worldwide and unrestricted access - and Turning the Pages represents the current state of this particular lending feature.

Originally created in 1998 by the British Library (the national library of the United Kingdom), Turning the Pages' technology was first installed into onsite kiosks to make some of the world's most valuable books accessible to library visitors. Now that the concept has been adapted to the Internet, that availability is global. The Web variant offers a selection of 10 historic volumes. These include a notebook of Leonardo da Vinci's, the Lindisfarne Gospels, Sultan Baybars' Qur'an, the Diamond Sutra (the world's earliest dated printed document), and George III's personal copy of Elizabeth Blackwell's "A Curious Herbal" - an 18th century botanical reference. Two more releases are planned for later this year.

Online, Turning the Pages uses Shockwave and JavaScript to deliver its content. (Alternative versions -presumably HTML-based- are also under production, but aren't accessible at time of writing.) Each volume is available in two file-sizes to accommodate various screen dimensions and connection speeds. While JavaScript enabled browsers will automatically choose the appropriate version for each visitor, the selection can also be made manually through the site's Home- and Technical Details- pages.

When chosen, each book opens into a new window with its own set of interactive controls, instructions, and an introduction to the particular manuscript. With the exception of the Diamond Sutra (a click-and drag scroll), pages are indeed turned by clicking the mouse pointer on the side of a page and dragging towards the center (though click-and-holding, without moving the mouse, also seems to work).

Along the bottom of the viewing space, a progress bar provides a "You Are Here" orientation in relation to each books' contents. Matching text and audio guides accompany each pair of open pages. (While there is no visual indication of an audio clip's progress or duration, control buttons remain highlighted while a feature is in use. So any time you're not sure if the narrator is done, or simply pausing for dramatic effect, just check to see if the audio button has returned to its neutral color scheme.)

The last button on the right generates a feature that will be especially useful to those viewing the "narrowband" versions of the books, which are about the size of a 640x480 screen and can suffer from having too much information for a relatively small image. The button launches a click-and-dragable, 3x magnifying glass which allows the visitor to view any part of the image in detail, and remains active even while listening to the narration.

On the far left, a Help button stands by with reminders about all this information as well as a collection of keyboard shortcuts - though Help's reference to "extra buttons" must apply to the onsite kiosks, as I didn't encounter any online. (In an odd little quirk, while text information boxes remain visible -and load new material- if you turn a book's pages via the keyboard or arrow buttons, the magnifying glass will vanish unless you stick to the click-and-drag utility.)

While the Leonardo Notebook might be the most valuable volume in the collection, and will probably have the highest recognition factor among site visitors, the visual interactive features of Turning the Pages are used to best advantage on publications like the Lindisfarne Gospels and the Sforza Book of Hours. A seventh century Latin text which also includes the earliest surviving Gospel in the English language (added centuries later for those who could read 'between the lines'), the Lindisfarne Gospels qualify as one of the world's most famous illuminated manuscripts. The roughly 4- by 5-inch Sforza Hours was owned by two of the most powerful women of the Renaissance, and illuminated by two of the outstanding artists of the period - and at least one of the book's playing card-sized paintings has been insured for more than da Vinci's Madonna of the Rocks.

Whichever book you choose, you're in for a visual treat, and the only thing missing from the interactive simulation is the sound of the page being turned. Perhaps that will be in the next version.

Turning the Pages can be found at http://www.bl.uk/collections/treasures/digitisation.html.