ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 

 Fig. 31. 



253 



Harting's Binocular Microscope. — Professor P. Harting has 

 suggested * a mode of making a binocular Microscope which has not 

 hitherto been described. 



The earliest binocular Microscope was that of Cherubin, 1678,t who 

 simply combined two complete Microscopes in one frame (Fig. 32 J). 

 Such a device could obviously only be made available with the lower 



Fig. 32. 



powers ; with high powers the necessary proximity of the object would 

 prevent the possibility of any joint convergence of the two objectives. 

 To obviate this difficulty Professor Harting placed two identical 

 lenses side by side (A and B, Fig. 33) with their axes at an angle 

 mo n with one another. If the object a 6 is at a distance equal to 

 twice their focal length, two images of it will then be formed a' b' 



* Das Mikroskop, 1859, p. 180. 



t ' De visione perfecta, sivo de amborum visionis axium concursu in eodem 

 object! puncto.' Paris, 1678, pp. 77-100. 



X This figure has been correctly copied by the engraver, but the eye-pieces in 

 A would appear to be too narrow. 



