770 



RECORD OF CURRENT RESEARCHES RELATING TO 



obtain with certainty illumination at definite angles witli Microscope 

 stands which are not fitted with a swinging substage. The inventor 

 describes it as follows : — 



" A perspective view of the apparatus (slightly reduced in size) is 

 shown in Fig. 5. It consists of a transverse bar of brass (1), at one 

 end of which, attached by a hinge (2), is a square brass plate (3), 

 which can be inclined at any desired angle. This plate is transfixed 



Fig. 5. 



centrally by a brass tube half an inch long, in which a second tube 

 (4) an inch and a half long slips easily. The slip-tube (4) is provided 

 at one end with the Society's screw, by which a 3-inch objective (5) 

 or any other preferred for the purpose, can be attached. The movable 

 square plate is provided with a spring catch (6) which fits into any one 

 of a series of notches in the edge of a brass quadrant (7), and thus 

 serves both to hold the plate in position and to register the angle of 

 obliquity. The transverse bar (1) slips in a groove on the upper 

 surface of a strong brass tube (8), fitted to the substage of the Micro- 

 scope. The bar itself has a longitudinal slot running nearly its whole 



