310 THE AMERICAN MONTHLY [Nov 



of this age, is as nearly "permanent" as any mount that 

 can be made. — Editor Natio7ial Druggist. 



Photo-micrographic Apparatus. 



R. GREENWOOD PENNY. 



The usual plan of introducing a table microscope into 

 apparatus for photo-micrography I have always deemed 

 a mistake, and I propose to show how, by a small addi- 

 tional expense, a plant which is far less bulky than that 

 usually supplied by opticians, and which is readily avail- 

 able for both high-and-low-power work, can be easily con- 

 structed. 



The larger microscope stands of English make having 

 a horizontal optic axis from 8in. to lOin. high, are, in my 

 opinion, ill-adapted for introduction into a photo-micro- 

 graphic system. They necessitate a raised platform upon 

 which to support the camera, and the illuminating appa- 

 ratus has to be raised in like manner, making the whole 

 plant unnecessarily heavy, cumbersome, and inconvenient. 



The employment of the smaller students' stands whose 

 horizontal optic axis is lower is open to the same objec- 

 tion, only in a less degree. 



Then, again, for very low-power work a table micro- 

 scope is wholly unavailable, as the body tube, even though 

 it be of large diameter, cuts off the peripheral rays from 

 any large object, so that it is impossible to photograph it 

 in its entirety. 



The photo-micrographic apparatus which I now com- 

 mend to the notice of my readers is thus constructed : — 

 The baseboard is 4ft. lin. long and 5|in. wide and fin. 

 thick. Two grooved stripsof wood are glued and screw- 

 ed on to the face of the base-board, and run from end to 

 end. Between these grooves, pieces of apparatus slide 

 freely, and can be firmly held in position by means of 

 clamping screws, such as are used for fixing halt'-plate 



