CH. IX] 



PROJECTION MICROSCOPE 



257 



be adjustable and with centering attachment. For objects which would 

 be injured by the heat allowed to pass the large water bath, a special 

 cooler is used next the specimen. For such cases the achromatic con- 

 denser must be especially constructed or the light would not be focused 

 on the object, and one would not get sufficient brilliancy for high 

 powers. Special condensers are now made admitting the use of the 

 special cooler, and if one has delicate objects which he desires to pro- 

 ject, like infusoria, or if he wishes to demonstrate the circulation of 

 the blood or living objects he should make provision for it in ordering 

 his apparatus. 



Fig. 208. 



Fig. 208. Leitz' Large Projection Apparatus {cut loaned by Wm. Krafft, 

 N. V.). 



As here shown the microscope part is turned aside, and the lowest of the three 

 condensers (300 mm. equiv. focus) is in place for proj ecting ordinary lantern tides. 



§ 4-!3- Specimen Cooler.— In order to project living objects 

 and delicate preparations the heat passing the large water bath must be 

 still farther eliminated. This is accomplished by a device of Zoth's 



