ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



121 



•stage is movable, rotatory, and is fixed by means of screws. The Abbe 

 condenser with iris diaphragm is central, and is adapted for raising and 

 lowering, and can be changed revolver-fashion for a cylinder diaphragm. 

 In order to protect the preparation from excessive heating in the event 

 of long-continued projection, a second water-chamber for alum solution 

 is inserted directly behind the Abbe condenser. For convenience of 

 change from microscopic to diapositive projection, the whole Microscope 



Fig. 25 



can be easily drawn off the bench and just as easily replaced. A 

 diaphragm arrangement is provided for stopping off interfering side 

 light. 



(4) Photomicrography. 



New Photomicrographic Apparatus.* — Mr. J. E. Barnard has de- 

 vised a photomicrographic apparatus with the following novel modifi- 

 cations. 



(1) Eigidity. The apparatus is supported on a cast-iron girder base, 

 thus combining the maximum of strength with the minimum of weight. 



(2) Focussing is accomplished in a novel manner. Kunning along 

 the base is a steel rod, provided with movable brass heads, at the end 

 of which is a grooved pulley carrying a silken cord kept uniformly tense 

 by weights. The cord passes up through the pivot supporting the 

 tail-piece, and is led over guide-pulleys to the fine adjustment. This 

 arrangement allows the Microscope and illuminating apparatus to be 

 swung aside without interfering with the fine adjustment arrangements. 



(3) The bellows are in segments, so that the whole or any part may 

 be used. The" supporting frames rest on brass tubes, running one on 



>each side of the entire length of the girder base. The contact with the 



* Trans. Jenuer (late British) Inst. Prev. Med., ser. ii. (1899) pp. 24S-50 (1 pi.). 



