In 1962 a specially designed semiautomatic case 

 was installed on an experimental basis. Its 40 mobile 

 trays were suspended between continuous chain 

 devices (fig. 138). By pushing electrical contacts, the 

 visitor could rotate the trays and examine at close 

 range each of the several hundred coins which were 

 displayed in this case.'^ 



All labels and background art work in these ex- 

 hibits, instead of being typewritten or iiand painted 

 as previously, were silk-screened. The results were 

 excellent even for the smallest specimen labels. 





Vig. 35. — Proof-finish Half Doll..\r, 1855. first 

 specimen struck at San Francisco Mint. 



i-'ig. 33. — The LMqut 1849 Double E.\gle, 

 pattern for the 20-dollar gold pieces first minted 

 in 1850. 



Fig. 34. — Unique Proof Double Eagle. 1854. 

 San Francisco Mint. 



Mounting coins for display has always presented a 

 challenge. Whenever possible, they were mounted 

 first in tightly closed individual boxes made of cellu- 

 lose triacetate K I\'. These are attached to the display 

 panel with small pieces of "Velcro," which consists 

 of a strip of nylon hooks which adheres to another 

 strip of nylon loops. When pressed together the hooks 

 and loops engage, creating a secure and easily ad- 

 justable fastener. This method permits easy removal 

 and replacement of display objects. In addition, by 

 this mounting method the coins are raised against the 

 background which accentuates them and produces a 

 very attracti\e overall effect. Where the size or shape 

 of a specimen precludes the use of boxes, the item is 

 often secured in place with a special paraffin wax. 



The windows of the display room in the Arts and 

 Industries Building were covered with filters which 

 allowed only 8 percent light transmission, thus re- 

 ducing the danger of harmful radiations and maintain- 

 ing a low general light level in the exhibit area. Dis- 

 turbing glare and mirror effects were also reduced, 

 and the individual internal lighting of the cases was 

 enhanced. This total lighting arrangement brought 



The display cases were provided with cold-cathode 

 internal lighting. The light boxes were equipped with 

 specially designed lenses of Lucite (mcthacrylate) for 

 maximum light distribution. These lenses also serve as 

 filters for some of the more damaging radiations, their 

 filter properties for ultraviolet being optimal at a 

 wavelength of 350 millimicrons The specially de- 

 signed cases arc equipped with self-locking folding 

 braces and 'i-inch polished safety plate glass. 



US.\M Report, 1962, p. 28. 



Fig. 36. — Proof-fi.msh Silver Dollar. 1879, 

 specially struck on the occasion of the February 

 20 reopening of the Xew Orleans Mint. 



24 



BULLF.TI.N 2 29: CO.XTRIIU -noXS FROM THK MUSEUM OF HISTORY .\XD TECHXOLOGY 



