32 KEPORT OF NATIONAL MUSEUM, 1893. 



case mirrors by whose reflections the general effect of an extended 

 miniature cave is produced. This is a very effective way of mount- 

 ing' exhibits, and the use of the mirrors seems to be an aid to the imagi- 

 nation of visitors, especially to young people who have never seen a 

 cavern. 



Another is for storing the great series of microscope slides of thin 

 sections of rocks which belongs to this dc])artment. It is thus described 

 by l»rof. Merrill : 



As it happened, we had in stock a nnniber of pasteboard boxes, sonic 03 mm. -wide, 

 143 mm. lonji, and 48 mm. deep, all inside measurements. Tbe dimensions of our 

 standard slide are 48 by 1.'8 mm. By means of two wooden partitions some 3 mm. 

 thick, running lengthwise, each box was divided into three equal compartments, the 

 partitions being hekl in place by glue reinforced by two small tacks at each end. 

 Heavy manila wrapping paper, such as we also had in stock, was then cut into 

 strips 25 mm. wide and as long as the sheet of paper would allow, in this case about 

 7 feet. These strips were theu bent into a series of folds, as shown in the accom- 

 panying illnstrati(m, the apices being rounded, not pinched flat. If carefully done, 

 the folds when crowded gently together act as a spring. Two of these folded strips 

 were then placed lengthwise in each compartment, and the slides introduced, stand- 

 ing on end, between the folds at the top. A box as thus prepared readily holds 3 

 rows of 50 slides in a row, or 150 altogether. 



Each slide is separated from its neighbor in the same row by a double thickness 

 of manila paper, which, owing to its manner of folding, acts as a spring, and avoids 

 all possible danger of breakage. When all the compartments are tilled, the space 

 between the tops of the slides in any row is but about 2 mm., but there is, neverthe- 

 less, no difiSculty in removing a slide or in getting at it to read the label without 

 removal, since, owing to the yielding nature of the paper, the top may be readily 

 drawn apart. In this respect the box ofl'ers a great advantage over those with rigid 

 compartments, such as are commonly in use. The first box was made merely as an 

 experiment. It proved so satisfactory that, for the time being at least, it is the form 

 adopted for storing the several thousand slides forming the museum collections. 



I have attempted to show the arrangement as above described in the accompany- 

 ing drawing (Fig. 6). In reality the slides are held much more firmly than indi- 

 cated, since the paper bulges and comes against both the front and back of the 

 slides the full length of the fold, instead of merely at the bottom. It will very 

 likely strike the reader that a better material than paper might be found. I can 

 only state that after considerable experimenting the paper was, all things consid- 

 ered, found most satisfactory.* 



The adoption of unglazed tiles, instead of wooden or paper blocksj 

 to support minerals, shells, and other small objects, is being considered, 

 and experiments, the result ot which will be announced later, are being 

 made by Mr. Charles Schuchert, of the Paleontological Department. 

 These tiles are rectangular, and of a soft buff' color, corresponding 

 closely to one of the standard shades used in the interior of our cases. 



A form of exhibition tray which has been in use for a number of 

 years is provided with a bevel front of peculiar construction, as shown 

 in the accompanying plate (PI. 32). These trays are covered with 

 black binder's-board, and a piece of colored paper or fabric is placed 

 on the bottom. This form of tray may replace the very objectionable 



This notice was printed in " Science," November 25, 1892. 



