668 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
the simple form of apparatus which I am about to describe is the result 
of these experiments. I have now had the apparatus in use for several 
months, during which time I have made a large number of very satis- 
factory photomicrographs of bacteria from fuchsin-stained preparations 
with an amplification of 1000 diameters. My photographs have been 
made with the 3 mm. ol. im. apochromatic objective of Zeiss and his 
projection eye-piece No. 3. I use a lar^e Powell and Lealand stand, 
upon the substage of which I have fitted an Abbe condenser. The 
arrangement of the apparatus will be readily understood by reference to 
the accompanying figure. 
A is the camera which has a pyramidal bellows front supported 
by the heavy block of wood B ; this can be pushed back upon the 
base-board which supports it so as to allow the operator to place 
Fig. 77. 
his eye at the eye-piece of the Microscope. When it is brought forward 
an aperture of the proper size admits the outer extremity of the eye- 
piece and shuts off .all light except that coming through the objective. 
C is the Microscope and D the Abbe condenser supported upon the sub- 
stage ; E is a thick asbestos screen for protecting the Microscope from the 
heat given off by the battery of gas-burners F. This asbestos screen 
has an aperture of proper dimensions to admit the light to the condenser 
D. The gas-burners are arranged in a series with the flat portion of the 
flame facing the aperture in the asbestos screen E. The concave metallic 
mirror G is properly placed to reflect the light in the desired direction. 
I have not found any advantage in the use of a condensing lens other 
than the Abbe condenser upon the substage of the Microscope. The 
focusing is accomplished by means of the rod ?*, which carries at one 
extremity a grooved wheel H, which is connected with the fine-adjustment 
screw of the Microscope by means of a cord. 
The focusing wheel J may be slipped along the rod i to any desired 
position, and is retained in place by a set-screw. The rod i is supported 
above the camera by arms depending from the ceiling, or by upright 
arms attached to the base-board. 
I have lost many plates from a derangement of the focal adjustment 
resulting from vibrations caused by the passing of loaded waggons in the 
street adjoining the laboratory in which I work. This has been over- 
come to a great degree by placing soft rubber cushions under the whole 
apparatus. 
