-,.i.; 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



For episcopk projection ivith lateral illumination, the lamp takes a 

 horizontal position, but is rotated laterally through 45°. A smaller 

 object-stage, adjustable vertically, is set up laterally ; the mirror is 

 rotated 9(r, and projection takes place as before (fig. 98). 



The whole apparatus is screened with black curtains, and on the 

 front is a round opening, reducible, at pleasure, for the different kinds 

 of projection. 



Fig. 98. 



New Vertical Illuminator for Metallurgical Examinations.* — 

 The firm of R. and J. Beck has brought out a new vertical illuminator 

 of the prism type, fitted with an iris diaphragm beneath the prism for 

 cutting off outside light, and a plate of stops so arranged that the position 

 of the beam of light impinging on the prism can be varied until parallel 

 light of the right angle is obtained (fig. 99). 



The principle is that a beam of light sent at right angles to the 

 optic axis of the Microscope is reflected by a prism or piece of cover-glass, 

 down upon the object, so that each objective acts as its own condenser. 

 It is probably the only means of illuminating objects mounted dry when 



* Knowledge, ii. (190o) p. 43; R. and J. Beck's Special Catalogue, 1905. 



