26 REPORT OF NATIONAL MUSEUM, 1893. 



logical specimens (.f all kinds, as well as in the departments of ethnology 

 and arclia'ology. 



Besides tliese tUere are over 10.000 unit boxes fitted with glass fronts, 

 which also, when necessary, are worked into the same system. 



The storage case, from which the idea was originally taken, was, I 

 believe, first invented by Prof. Strickland, of Cambridge, England, and 

 afterwards modified by .Mr. Osbert Salvin. As at first constructed in 

 the ^'ational Museum, the sliding strips in the storage cases were tri- 

 angular pieces of hard wood, 1 inch in width and one-half inch wide 

 at the top, sloping to one-eighth inch at the bottom. (PI. 7, fig. 3.) 

 These were nailed horizontally close together upon each side of the case, 

 whde in the grooves thus formed were received the corresi)ondiug strips 

 nailed upon the two sides of each drawer— stri])s originally of the same 

 size but trimmed slightly in order that they might run smoothly. 



The top, or thin edge, of the slide-strip was always placed 1 inch 

 below the top of the unit drawer, or 2 inches below the top of the glass- 

 covered unit box, and since the depth of these unit drawers and unit 

 boxes was always an even number of inches, a drawer of any depth 

 could be used, from 2 to 14 inches, and a corresponding drawer of any 

 depth could be placed above or below it. Any compartment could thus 

 be filled with unit drawers of any desired depth. 



The first improvement in this mechanism grew out of the desire to 

 secure still greater tightness. The interior of the compartment was 

 lined wifh zinc, and the strips were nailed on the inside of the zinc. 

 This proved obiectiouable on account of the nail-holes. 



The next step was to make the slide-strips at the sides also of metal, 

 and to accomplish this many experiments were tried, and finally 

 arrangements were made with a firm in Philadelphia engaged in manu- 

 facturing corrugated iron. It was necessary for the Museum to have 

 especiallv constructed a set of dies and rolls for rolling the metal into 

 the desired shape (PI. 7, fig. 1), and also to import Florence tin of extra- 

 ordinary thickness, the kind ordinarily used in the United States not 

 being sufficiently strong. This experiment proved satisfactory, and 

 150 cases of this type have been for four years in use in the Museum, 

 and have stood the test of wear. The only objections arise from the 

 slight roughness where the sheets of tin are joined together, which IS not 



serious, and the fact that the outer ends of the metal ridges, which 

 were of course hollow, had a tendency to bend when the drawers were 

 drawn so far as to make a strong leverage upon the points. This, how- 

 ever, has been satisfactorily remedied by the use of triangular plugs 

 of hard wood, technically called "dutchmen." which are driven into 



the openings. . 



Out of these experiments still another form of storage case resulted, in 

 which the metal was placed outside of the woodwork instead of inside, 

 being soldered upon the outside of a substantial framework of wood, 

 while the strips upon the inside were of wood arranged in a new way. 



