616 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



should be added as required. The board is perforated by a hole large 

 enough for the mirror and base rods to be passed through, but smaller 

 than the brass plate to which the water-cell and mirror-adjuster are 

 attached. This plate is firmly screwed to the board. The various 

 items of apparatus slide on the base rods, and ordinary objectives are 

 used. A sufficient darkening of the room is obtained by very dark 

 opaque blinds on spring-rollers, their edges being boxed up. 



(4) Photomicrography. 



Observing Prism for Photomicrography. — TLis apparatus, fig. 121, 

 devised and made by Messrs. E. and J. Beet, consists of a right-angle 

 prism fitted in a tube of the same length as and at right angles to the 



Ft;. 12j. 



ordinary Microscope-body. The tube screws on to the object-glass end 

 of the instrument. "When the Microscope is in a horizontal position the 

 tube may be connected with the photomicrographic camera and all the 

 observing done through the supplementary body through the observing 

 prism. To take a photograph, the prism may be instantly displaced by 

 pressing a milled head, and the light then passes directly up the Micro- 

 scope-tube into the camara. So accurately are the parts constructed 

 :md adjusted that there is no loss of definition and Amphipleura pellucida 

 can be perfectly resolved. 



Photomicrography.* — F. M. Duncan's First Steps in Photomicro- 

 graphy, which only claims to be a handbook for novices, consists of a 

 simple and almost non-technical account of the methods and apparatus 

 employed in the production of photomicrographs. It deals with low, 

 medium, and high-power work, developing, printing, preparation of 



* Louuon, Hazell, Watson & Vine)-, 1902, lOi j>p., with illustrations. 



