IO2 



VISION WITH THE COMPOUND MICROSCOPE 



A form of this binocular eye-piece was made by Professor Abbe 

 with the ingenuity and thoroughness characteristic of the firm of 

 Zeiss ; but in spite of its beauty as an optical instrument, and its use- 

 fulness as applicable to any tube, and especially the shorter tubes 

 to which the Wenham 

 binocular could not well 

 apply, the double image 

 in the right-hand tube 

 was most conspicuously 

 apparent, greatly inter- 

 fering with the perfection 

 of the stereoscopic image. 

 On this account chiefly it 

 has not come into general 

 use. We are nevertheless 

 indebted to the firm of 

 Zeiss for the introduction 

 of a very satisfactory 

 form of binocular instru- 

 ment, of which we can 

 speak with unconditional 

 praise. It is designated 

 as Greenough's binocular 

 microscope, and we can 

 confidently affirm that 

 it furnishes an accurate 

 solid and withal an erect 

 image, so that for all the 



FIG. 79. Greenough's binocular microscope (1897). 



purposes for which the use of the binocular is at present desirable it ac- 

 complishes what is sought, and will be found invaluable for zoologists, 

 botanists, and embryologists. The microscope is shown in fig. 79, 



