ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
107 
being much lighter and more portable. The total weight, inclusive of 
a large shutter, only amounts to 16 lb. On a moderately thick base- 
plate A (fig. 14) rise two wooden pillars B, which, by means of the two 
holders C and D, carry the two photographic cameras, the lower small 
Fig. 14. 
one E for small plates 8x8, and the upper one F, which fits into^the 
lower, for larger plates, 16 x 18. 
This division of the camera into two parts is very useful in working 
with petroleum light. 
