310 SUMMARY OF CURUENT RKSKARCHES RELATING TO 



that an object (piece of a fly's eye) less than 1/16 in. in diameter 

 can bo exhibited clearly and with good definition enlarged to 10 feet, 

 and a bee's sting to 20 feet. 



Two mirrors, a and h, are supported by the arms I and k, on which 

 they swing. The arm I is attached to the ring /(, which rotates on the 



Fio. Gl. 



inner cylinder by the milled head m. The cylinder being directed to 

 the pole the mirror a by the rotation of the ring h will bo made to 

 follow the sun. The ami Tc is similarly attached to the ring i, which 

 rotates by hand, and by which the mirror h can be set so that the sun- 

 light is thrown through the condenser. The inner cylinder which is 

 directed to the pole is connected by a hinge joint n to the base plate 

 0. The optical part consists of the convex and concave lenses c d, 

 small condenser e, and the objective g. The condenser and objective 

 with the stage / slide along two rods s s, and are clamped by the 

 screws r r r. The fine adjustment is at t. The lens e can be adjusted 

 vertically or laterally by screws not shown in the fig. 



The parts noo are of wood 4 in. by 3/4 in. and 22 in. long. 

 They can be turned about q, which is immediately under the centre of 

 the mirror b. The piece p extends 2 in. beyond either side of n o, 

 and is screwed to the window-sill. The three pieces j; n o all turn 

 independently, and in use o o is turned to point to the place where 

 the image is to be shown. 



The apparatus can be used with the electric or lime light. 

 Clockwork could be applied to it. 



Thompson's Projection Microscope.* — W. G. Thompson describes 

 the following adaptation of a Microscope (designed by himself and 

 Dr. J. W. Roosevelt) " as a sort of magic lantern " for class-room 

 demonstration, which he has found extremely useful, cheap, and 

 practical, 



A large common kerosene " duplex " lamp (fig. 62, facsimile of 

 original) is the illuminator. Superfluous light is cut off by a piece of 

 6-in. stove-pipe, which fits over the lamp-chimney, and rests upon a 

 horizontal collar C, of stove-pipe metal. The collar prevents the 

 pipe from coming down too far upon the lamp, which would cause the 



» Science, iv. (1884) pp. 540-1 (1 fig.). 



