ELEMENTARY PHOTO-MICROGRAPHY. 

 PIvATE XV. 



Crystal of Sal-ammoniac by DOUBLE LIGHT. 



Enlarged from negative. 

 TAKEN WITH OIL LAMP. 



Amphipleura Pellucida. X 4000. 

 Showing lines breaking into dots. 



Exposure, One' Hour, 

 oil immersion, 1.4 N.A. Condenser oiled to the slide. 



