<//. IX} CABINETS sL\D TRAYS /-'OK PREPARATIONS 



267 



$ 372. Slide Trays with Tongue and Groove. In the first trays the edges 

 were square and sharp. These were rounded in later trays, but there still re- 

 mained a defect, for if one wished to pile up five to twenty trays on the table, 

 they would not stay in an even stack. To remedy this defect the long way of 

 the frame was tongued on one side and grooved on the other as shown in Fig. 

 213. This is a great improvement as one can make even stacks of 25 or 50 

 trays, and they will stay in position. Furthermore it renders the groups of 5 

 trays stored in the locker compartments much easier to manage, as one can re- 

 move any of the five trays without getting the others disarranged as so often 

 occured with the old form, lacking tongue and groove. 



O 



FiG. 213. Slide Tray zuith Cross Pieces on one Face to retain the Slides in 

 Rows. {Dr. Greenman' s improvement.) A tongue and groove serve to hold 

 the trays in position ivhen they are piled up. (A. about 1-8, and C. about 

 natural size.) The corners of the tray frame are held in place by the corru- 

 gated pieces of iron used in the construction of picture frames . 



\ 373. Slide Trays with One Side Divided. A defect of the trays for 

 storage is the ease with which the slides get disarranged unless the tray is en- 

 tirely full. To avoid this defect Dr. M. J. Greenman of the Wistar Institute 

 divides one face into rows of the right width for receiving the slides. Then 

 while the slides in any single row might get displaced those of neighboring 

 rows cannot become mixed (Fig. 213 A. ). One side of this tray is smooth and 

 can be used for ribbons of sections like the original tray. Dr. Greenman stores 

 the trays in metal cabinets, each tray having a separate pair of " runs" as is 

 shown in Fig. 211. The author of this book adds the cross pieces to divide 

 the tray into rows and also has the frame grooved and tongued (J> 372). Thus 



