THE AMEKICAN MONTHLY 



[January, 



ones, as regards convenience, to say 

 nothing of expense. Dr. Sternberg, 

 if we recollect aright, uses 4X5 

 plates for all of his work. Dr. Van 

 Heurck's photograph of the A. 

 pelhtcida., which we have at hand, 

 is only 3^ inches in length, and 

 shows but a small portion of a frus- 

 tule. The fine photographs of di- 

 atoms by Mr. J. D- Cox are mounted 

 very neatly on cabinet cards. Some 

 of the most attractive mounts we 

 have seen are from Dr. G. A. Pier- 

 sol, who has adopted a plain, deli- 

 cate yellow card six inches by eight, 

 for prints evident- 

 ly made from 4X5 

 plates. Probably 

 the amateur will 

 usually be content 

 with plates no 

 larerer than this. 



moved back and forth without get- 

 ting out of line. In some instances 

 the camera requires to be raised on a 

 block. It should then be securely 

 fixed in position, and it is well to 

 screw the block firmly to the base- 

 board. 



One of the simplest arrangements 

 is that of the Scovill Manufacturing 

 Company, repres'ented in fig i. 

 The entire apparatus is placed on a 

 solid board, ^vhich, to avoid jars, 

 rests upon rubber cushions. The 

 source of light is Carbutt's lantern, 

 already figured on page 225 of the 



Fig. 4.— HiUisch & Lonib Photo-Microgniihic Apparatus. 



which is a very convenient size. 



We come now to consider the ar- 

 rangement of the camera in connec- 

 tion vv'ith the microscope. A heavy, 

 perfectly flat and smooth board 

 should be provided as a common 

 base for microscope, camera, and if 

 possible, also for the lamp or helios- 

 tat. Place the microscope on the 

 board with the body-tube perfectly 

 horizontal, and arrange the camera 

 so that a line passing through the 

 optic axis of the microscope will 

 pierce the centre of the ground glass 

 of the camera. Then see that the 

 whole apparatus is in line, and mark 

 the position of camera and micro- 

 scope. The best way to do this is to 

 glue some strips of wood around 

 the base of the microscope, and 

 along one side of the camera. The 

 latter should be very carefullv ap- 

 plied, so that the camera may be 



preceding volume. This outfit can 

 be purchased without the lantern if 

 desired. 



We now come to Mr. Walmsley's 

 outfit, which is illusti^ated in fig. 3. 

 It scarcely requires any further de- 

 scription, as the whole design is so 

 clearly evident from the cut. How- 

 ever, the focussing device deserves 

 especial mention. It was applied by 

 Mr. Walmsley some time ago, and 

 was also independently used by Dr. 

 Sternberg in a slightl}' diftei"ent form. 

 A groove is turned in the periphery 

 of the fine adjustment screw, around 

 which a small cord is passed, and 

 carried through a succession of screw- 

 e3'es on either side of the base-board 

 to the rear, where a couple of small 

 leaden weights are attached to its 

 ends, thus keeping the cord taut. A 

 very slight pull on either side, whilst 

 the eye is fixed upon the image on 



