REPORT OF ASSISTANT SECRETARY. 27 



Instead of se])arato triangular strips, 8-iuch boards of oak or ash, one- 

 half inch in tliickness, are jtiluod and nailed close together ui)on the sides 

 of these strips. In these boards are Avorked at intervals of every half 

 inch grooves one-half inch in width and about one-half inch in depth. 

 (PI. 7, fig. 2.) The side« of the case are thus provided with a series 

 of parallel, liorizontal grooves separated by half-inch bars, which 

 represent the triauguhir strips formerly described. To correspond to 

 these grooves a new device is employed for the support of the trays. 

 Instead of the strip which was formerly nailed at the side, the lower edge 

 of the tray projects with a triangular section beyond the iilane of the 

 sides, as shown in the diagram. (PI. 8, fig. 1.) This device is appli- 

 cable to light drawers not over 4 inches in depth. The drawer of the 

 old type, however, works advantageously in the same groove. 



In both the metal-lined and metal-covered cases, as just described, a 

 very effective means of closing the front is secured by the use of rub- 

 ber tubing fastened in a groove in the zinc-covered front edges of the 

 opening, against which a solid wooden door is firmly pressed by means 

 of a special form of combined bolt and lock, as shown in the accom- 

 panying sketch.* (Fig. 1.) 



Many improvements have been made in the past ten years, not only 

 in the sliding mechanism, but also in the methods of making the cases 

 moth and dust-proof. 



One moth-proof case is a modification of the form originally devised 

 by Mr. William Brewster, of Cambridge, Mass. 



The most jierfect example of the moth-proof case which has been pro- 

 duced, is one especially modified from designs by Mr. J. S. Goldsmith, 

 for the reception of the type specimens in the mammal collection. This 

 case contains 8 drawers, 3 by 4 feet. Most of the drawers are 2 inches 

 deep, but others of any required depth can be used. The drawers are 

 of pine and have a solid wooden bottom, although one of three-ply 

 veneer would doubtless be an improvement. The system of construction 

 is that already described, with grooved wooden boards inside of a zinc 

 cover. The drawers are provided with the ordinary triangular slide- 

 strips. The frame of the case which supports the slide-ra(;ks inside is 

 covered with zinc outside, and is of i^ine 3 inches wide and seven-eighths 

 of an inch thick. The frame is covered with sheet-zinc, weighing 16 

 ounces to the square yard. The zinc-covered case, which is 38 inches 

 long, 51 inches wide, SIJ inches high, is then i)laced in a case of hard 

 wood, whose dimensions in the clear inside are 2 inches longer and 2 

 inches higher than the case, which, when pushed into place, fits against 

 the back of the wooden case — the front edge of which projects about 3i 

 inches beyond the outer edge«of the zinc case — but is separated by seven- 

 eighths of an inch from its sides, bottom, and top. This space is filled 

 by pine strips, 3 inches in width and sev^en eighths of an inch in thick- 



'Tlie text figures have been grouped into plates, following Plate 57. 



