Suppose you have a priceless historical document and you need to preserve it for, say, a few centuries or so. Who you gonna call?
That was the question facing the New York State Library and New York State Education Department (NYSED) recently. They had President Abraham Lincoln’s first handwritten draft of the Preliminary Emancipation Proclamation, and wanted to put it on public view – but in an impregnable housing that would protect it from deterioration indefinitely. They called NIST. Want a look?
Now, like so many of the nation’s most precious historical documents, the draft is protected by an encasement system custom-designed, constructed, and outfitted with an array of sensors by PML scientists.
The sealed, sandwich-like encasement is made from two halves precision-milled from a 690-pound solid block of aluminum by NIST’s Fabrication Technology Group. Tolerances ranged from plus or minus 1/1000th of an inch up to
25/1000th of an inch.
One of the most critical aspects of the machining was the back of the base component, which is about 3/32nds of an inch thick. It must be flexible to compensate for most of the changes in atmospheric pressure by bending in and out to alleviate strain on the glass viewing window.
Then NIST scientists equipped the case with a custom instrument suite that records pressure of the gas in the case (96% argon, and 4% oxygen), temperature, relative humidity, and oxygen content every 15 minutes. On-board electronics collects the measurements and updates them to computer storage. Software tracks those readings, and if there’s a serious change, the system will send an email to NYSED so that they can take immediate action as appropriate.
By the way, NIST has made cases to house other precious documents too: