A special exhibition case -- unique in the world -- has been custom-built for the most valuable and fragile treasures to be displayed in the "American Treasures" exhibition. The show is the largest permanent exhibition ever mounted by the Library of Congress.
The "top treasures" case, which weighs 3 tons and is 12 feet long and 10 feet high, was built according to the highest standards of preservation and security. It is reserved exclusively for the Library's rarest and most valuable items. Initially, the case is being used to house a group of documents in Thomas Jefferson's own hand relating to the creation of the Declaration of Independence, including the "rough draft" and an even earlier fragment, on display through July 31.
Because of preservation considerations, the Library's "top treasures" will be shown on a rotating basis. For example, George Mason's 1776 "Virginia Declaration of Rights," which laid the groundwork for the Declaration of Independence, will be on view from Aug. 1 through Oct. 31.
The case was developed by the Library of Congress, in cooperation with Explus Inc. of Dulles, Va., in association with Carl F. Booth and Co. of New Albany, Ind.; Creative Edge Corporation of Fairfield, Iowa; and Norment Industries of Montgomery, Ala., all of whom made contributions of materials and expertise.
The case consists of a high-hard-steel display chamber within an exterior of maple veneer with mahogany inlays. On either side, two large viewing windows are glazed with a specially rated ballistics polycarbonate and glass laminate. Temperature and humidity can be maintained within minimum tolerances of plus or minus 1 degree Fahrenheit or 1 percent humidity. Although currently set for the optimum preservation conditions of 50 degrees and 50 percent relative humidity, higher temperatures can be maintained.
