WONDERS OF THE MICROSCOPE 24^ 



taken from the underside of the winu- of the 

 common Wall liutterMy. It ma\- also be said of 

 these scales that, althouoh of almost immeasurable 



I'ig. 1^4. Scales, oi' dust, from ilie wing of 

 a moth 



thinness, they are found to be composed ot several 

 layers, plain and ornamental ; and have markinq-s 

 of such delicacy and beaut\" that opticians 

 frequently use them as test-objects tor obtaining 

 accuracy in microscopic lenses. 



The hairs of insects too are curious and well 



