The Microscope. 273 



class series, the ocular No. 1 or A, any the light, (as previously 

 stated) that of a student's lamp, reflected by the concave mir- 

 ror. The plate was one of Carbuth J. C. B. brand, at that time 

 the quickest of any in the market. Five minutes was the length 

 of exposure determined upon and given, and the result (with 

 ferrous oxalate development) was a most excellent negative, 

 which is now lying beside me, and which (en passant) is '"'■not 

 for sale" being my first born. Beside it lies another and far 

 better negative from the same object, made recently with iden- 

 tically the same apparatus and fixtures in one and a half min- 

 utes; the saving in time being due to the employment of the 

 more sensitive plates now made by the same maker, and alka- 

 line pyro development. Another negative from the same sub- 

 ject also lies beside the others, made in one minute with the 

 same lens, and lighting, but employing a comera with a bellows, 

 that permitted the banishment of the eye-piece, and this latter 

 negative is incomparably finer in every particular than either of 

 the others. It will thus be seen that in making my first photo- 

 micrograph an eye piece was employed, although as stated I 

 never use one now. 



Subsequently Dr. F. W. Mercer, of Chicago, without any 

 previous knowledge of my initial attempt, devised a similar 

 form of camera which may be used upon any microscope large 

 enough to carry it, with or without employing the eye-piece, as 

 desired. This camera is now being made by the Scovile Manu- 

 facturing Company in their usual masterly workmanship, and 

 is sold at a very moderate price. For quickly producing a faith- 

 ful and permanent image of an object under examination, with 

 out any change being required in the microscope or illumination, 

 it serves a most useful purpose ; but its field of usefulness as 

 well as that of view, being extremely limited, it can only be 

 recommended as an ajunct to a better camera. 



More recently Mr. H. F. Atwood, of Kochester, devised an 

 ingenious combination of a microscope and camera, which may 

 be briefly described as follows : A cone shaped box about thir- 

 teen inches in length, carries at the larger end a focussing 

 screen and plate holder for plates, 3| x 4^ inches. At the 

 smaller extremity is permanently attached a simple form of 

 microscope stand without eye-piece, and provided with the so- 



