ZOOLOGY, AND BOTANY, MICROSCOPY, ETC. 



50;" 



an unusually brilliant image is projected. The self -regulating lam]* has 

 a current-strength of 30 amperes and 48 volts E.M.F. ; higher voltages 

 must have a corresponding rheostat equipment. The lamp can be 

 centred, and has a three-fold adjustable collective lens system of 210 nun. 

 diameter, and is protected from the heat by a hard glass disc. A cooling 

 chamber stands in front of the lenses. The arrangement for microscopic 

 projection (fig. 96) consists of a two-fold condenser, large cross-stage with 

 preparation cooler, Microscope tube with iris, rack-and-pinion adjustment, 

 micrometer screw, triple objective, and ocular revolver, all mounted on 

 an optical bench. 



For diapositive projection the movable stage with Microscope tube 



Fig. 97. 



is, by means of a hinge, swung aside. Simple projection objectives 

 are set up in lieu of the Microscope condenser. A dispositive holder. 

 with exchange-frame and apertures 13 by 13 cm., and a plate with 

 clamps for projection of larger section-preparations, are placed before 



the large cooler. 



For episcopic projection with downward illumination (tig. 97) the 

 lamp is slanted upwards on a strong axis in a vertical plane at an 

 angle of 45°, and the object placed on a large stage is thus illuminated. 

 The projection objective of 400 mm. focus is rotated into the optical 

 axis. A mirror over the lens-system receives the image and reflects it 

 at 90° into the projection-objective. 



