and Laboratory Methods. 



Ill:} 



LABORATORY PHOTOGRAPHY. 



STEREO PHOTO-MICROGRAPHY. 



Mr. John G. Baker has sent us a number of very interesting micro-stereographs 

 of insects and the following description of the apparatus and methods employed 

 in making them. The work was first publicly exhibited and described June 6th, 

 1899, before the Photographic and Microscopical Branch, Chemical Section, of 

 the Franklin Institute. 



Figure 1. 



This camera was constructed for the purpose of making stereoscopic pictures 

 of small objects. 



My first attempt was in fitting up a stereoscopic camera for the purpose, but 

 the result was not at all satisfactory, although it made some very fair negatives. 

 The camera proved to be very much too short, and the lens and object had to 

 be changed from one side to the other, all of which made it very inconvenient. 



The next attempt is embodied in the instrument shown in the illustration. It 

 was originally a lantern slide camera, which was altered to what you now see. 

 The shutter used is a 4 x 5 " Victor." To the front of this was fitted an attach- 

 ment to carry the lens and also to hold a reflector for properly illuminating the 

 object. In the rear of the shutter, instead of a lens, a ring was placed to cut 

 off any reflected light. The rear end of the camera has been fitted up to receive 

 a 5 X 7 plate-holder, but in such a way that it may be used in two positions, so 

 that each end of the plate may be exposed independently of the other. The 

 plate-holder rests against a partition with an opening in it of a size just sufficient 

 to cover one-half of the plate. 



The lenses for very small objects are achromatic objectives that are used in 

 the microscope, but for this work are changed somewhat, to better answer the 

 requirements. 



The trouble found with them for the work was their narrow angle of view 

 and extremely small depth of focus, and each of these faults had to be remedied 

 before it was possible to make a satisfactory negative. It was also found that 

 the rays of light, in passing through the lens, had a tendency to fog the plate by 

 coming in contact with fiat surfaces, even when these were blackened with the 



