

Bt DE. E. abbe, Professor in Jena. 



^ad before the Bristol Microscopical Society ^ JDecember I6thf 1874. 



PeEFACE by the TfiANSLATOE. 



Under the title here given, Dr. Abbe has published in the 9th 

 Tol. of Schultzes Archiv fur Mihroscopische Anatomies the results 

 of some important investigations which I cannot but think must 

 prove of great interest to all who value the microscope as an 

 instrument of scientific research. In offering a translation of 

 this essay to the readers of our journal, I venture to remark that 

 the exposition therein contained of optical principles involved in 

 the phenomena of microscopic vision, and their application to the 

 construction of the microscope, deserve to be as widely known 

 amongst microscopists and students of physical science in England 

 as in Germany. It will also be seen that many facts of real 

 practical value are presented in a new and intelligible point of 



