APPENDIX. 151 



Binocular Photography. — Stereoscopic photo- 

 graphs may be produced by Stephenson's Binocular 

 arrangement, Polycystinge and Discoidal Diatoms 

 form beautiful objects when seen in the Stereoscope. 



The prisms should be placed as near the back of 

 the objective as possible, and an ordinary stereos- 

 copic camera substituted for that already mentioned. 



Wenham's and most other arrangements are com- 

 paratively useless, as the light is not the same on 

 both plates, and the plates themselves require to be 

 placed at an inconvenient angle. 



