The world's largest library uses the latest technology to study and scan ancient books, maps and other historical artifacts.

The Library of Congress has nearly 150 million items in its collection, including at least 21 million books, 5 million maps, 12.5 million photos and 100,000 posters. The largest library in the world, it pioneers both preservation of the oldest artifacts and digitization of the most recent–so that all of it remains available to future generations.

I recently took a tour of two LoC departments that exemplify this mission: the Preservation Research and Testing Division in Washington, D.C., and the National Audio-Visual Conservation Center in Culpeper, Va.

The library's preservation specialists use the latest technology to study and scan ancient books, maps and other historical artifacts. One process, called scanning electron microscopy, allows them to create elemental maps of manuscripts, identifying the chemical nature of inks and pigments, or the paper itself. Imperceptible changes made by artists appear plain as day when viewed using x-rays.

X-rays, however, aren't easy to work around. One new technique, hyperspectral imaging, offers similarly revelatory results in the darkroom: ultra-high resolution scans of documents, imaged under sharply restricted wavelengths of light, show details denied to the naked eye. Viewed at sharp angles, old documents even reveal data about the woodblocks used to impress them onto the page.

It's not all about moldy maps and tomes, either: thanks to the poor quality of consumer media, techniques are already being developed to recover information from damaged examples. Researchers already understand, for example, why using sticky labels increases the likelihood of failure in CDs and DVDs. (LightScribe etching has no apparent negative effects). So when the work of today's unheralded geniuses end up as priceless, rotting museum pieces, the preservers will be ready.

An ancient book presents the typical problem for archivists: how to better understand something that may be destroyed simply by the act of examining it? Researchers have adopted policies which forbid sacrificing part of an item in the hope of learning more about it.

"We can't afford any damage to anything," said Eric Hansen, chief of the Preservation Research and Testing Division. "Never take a sample; be completely nondestructive. … We know there will be advances in technology and that current techniques will become outmoded."

"We can map the elements, the chemical components," said Jennifer Wade, scanning a centuries-old but well-preserved copy of Platina's The Lives of the Popes. "We can simulate changes in heat, cold, and humidity. [But] all we do is provide information about treatment. Others make the restoration decisions."

Fenella France, a research chemist with the Preservation Research and Testing Division, uses a 39 megapixel camera to take high-resolution images of documents ranging from renaissance-era maps to American state papers.

"We don't filter at the camera, we illuminate with small wavelengths," Fenella said. "We're creating a reference set of samples. We can't take samples of the documents themselves–it's just not going to happen"

This technique creates a set of images like a 'stack of cards,' all identically framed but revealing a different spectral face of the subject.

On the plan for the city of Washington designed in 1791 by Pierre L'Enfant, a hidden street plan emerges under IR light. A design for a circle emerges on 16th and K.

"It's incredible, it's humbling. It might be 6 p.m. and I'll be exhausted but I think, 'I can't complain–I'm working with the Gettysburg Address!'"

The Gettysburg Address exists on her computer as 8 different documents, each representing a different waveband in the visible spectrum. But only some show the mysterious fingerprint residue that may be Lincoln's own.

"In the next 5-10 years, I wouldn't be surprised if they could pull residual genetic information from the documents. [This is why] one of our foci is making sure that we don't interfere with future research."





Among the finds: tracings of an earlier document on a Marco Polo map that dates to 1480. Lost text, revealing the cartographer, on 1516's Carta Marina. James Madison's debate papers, it turns out, contain hidden revisions.

"If it's fragile, even researchers have trouble with it," France said."I want to make it acessible."

"We pretty much know that the Vinland Map contains titanium dioxide in a form that didn't exist until modern times." – Eric Hansen

Far fom the bustle and majesty of Capitol Hill, a former nuclear bunker has become home to an unprecedented effort to catalog the nation's creative works. And while the media is more recent than that dealt with in D.C's basement labs, plenty of technical challenges remain.

The National Audio Visual Conservation Center, near Culpeper, Virginia, once contained billions in cash, squirrelled away to kickstart the economy in the event of an atomic apocalypse. Beautifully renovated, it now has 175,000 square feet of offices and laboratories, 135,000 square feet of collections storage, and 55,000 square feet dedicated to storing dangerous nitrate film in optimal conditions. There are more than a million films, television shows, DVDs and games already in its collection.

And it grows, day in, day out. Delivered to loading docks, thousands of items make their way through processing areas until finding a permanent home in the vaults.

Gregory Lukow, chief of the motion picture, broadcasting and recorded sound division at the campus, said that it was staffed by about 100 techs, engineers and other workers. Many items are digitized to ensure their preservation, and to allow researchers to view them remotely in D.C reading rooms. They also host public screenings of classic movies at the in-house cinema.

Most of the collections arrive via the copyright registration process. Though works receive copyright protection at the moment of creation, registration provides more legal options in court disputes, ensuring what Lukow called "a tidal wave of material" for the campus to process. But a lot of the material is old — and not all of it is in good nick.





Gregory Lukow of the Library of Congress shows off the intake bins at their audiovisual campus in Culpeper, VA., packed with the cultural output of a nation. Millions of items are added every year to LoC collections. Highly sensitive items, such as digital prints of movies playing in theaters, often arrive under assumed titles to reduce the likelihood of interception.

"We don't want videotape coming in in 5 or 10 years time. Magnetic media is a losing proposition" – Gregory Lukow





Into the Film Storage Vaults: maintained at 39° at 30 percent relative humidity, nitrate film is divided into 124 individually fireproofed chambers, each able to hold about 1,000 cans. Each is designed so that even if a particular reel goes up in flames, it can only damage those in the same insulated cubbyhole. Total capacity: 145,056 cans. Films removed from the vaults must first go through an acclimation chamber before being exposed to normal temperatures and humidity.





Gregory Lukow describes RCA Selectavision, a video format so homely it is denied even the ironic contemporary cachet enjoyed by LaserDisc and 8-track.





Gregory Lukow explains the workings of one of the Library's basic tools: a flatbed film viewer designed to let staff play fragile films without the use of projectors and potentially damaging bulbs.





Scott Rife, senior system administrator, explains the library's digital storage system in this video clip: a tape library with 37,500 slots, each able to store 1TB of data. "That's 37 petabytes. As far as we know, this is the largest digital preservation operation in the world." Even so, they remain committed to preserving film as film: "We wouldn't preserve 35mm as digital right now."





James Snyder, senior systems administor, explains the challenges involved in capturing hundreds of channels of archivable broadcast material. When completed, the Packard Campus's "Live Capture" room will grab 120 video streams from satellite and FM television, 90 DirectTV channels and 20 DISH Network channels. 72 Mac Minis will capture the output of 42 internet radio stations, 10 FM radio stations, and much of what's played on the XM/Sirius satellite radio service. Each machine is able to capture two sources at once: if an individual capture station fails, another picks up the load. Playlists, as cultural snapshots, are themselves important artifacts





Welcome to the Critical Listening Room. James Smetanick describes the work of an audio engineer tasked with preserving sound recordings. The environment is perfect: non-parallel walls and deeply-pocked paneling kill standing waves and reflections. A custom-made Simon Yorke turntable is good enough for government work: maple knobs not required. "I can't complain about coming in each day," Smetanick said.





The Packard campus contains a huge variety of old and obsolete machines used to view, cut or otherwise manipulate media. It's not just for show, either: obscure formats will become unreadable if the vintage tech used to play them isn't maintained.