459 



ON A METHOD OF PREPARING STEREO- 

 PHOTOMICROGRAPHS. 



By A. C. Banfield. 



{Read October 26*7*, 1909.) 



Plates 37-40. 



In the paper which I now have the honour of presenting 

 to you I wish to draw your attention — at least those of 

 you who are photographers — to the singularly beautiful results 

 which are obtained by applying stereoscopic methods to photo- 

 micrography, results which, in possessing the third dimension 

 of depth, or distance, tell us more of the actual shape of an 

 object in a single glance than is possible by any monocular 

 photograph, however good. 



Let us briefly dwell on the nature of a stereoscopic photo- 

 graph, and understand why it is that two apparently similar 

 photographs of a given object should give us such a wonderful 

 sense of relief when examined through a stereoscope. I say 

 apparently similar, for a difference exists between the two 

 pictures, in most cases so small as to be imperceptible when 

 viewed by the unassisted eye, but it is nevertheless there, and 

 it is this minute difference which the brain recognises when the 

 two photographs are viewed by the instrument which we know 

 under the name of the stereoscope. 



The dissimilarity of the two pictures is that which is caused by 

 each of our eyes receiving a different impression of an object, 

 due to their angular separation. It is entirely due to the 

 separation of our eyes that we are enabled so readily to 

 locate the position of an object in space with reference to others. 



Turning now to practical methods, stereoscopic photographs 

 of ordinary objects, views, etc., are taken by means of two 

 separate cameras, for convenience mounted parallel to each 



