576 M. A. AIXSLIE ON AN ADDITION TO THE OBJECTIVE. 



I have also tried to effect the conversion in the case of a Holos 

 4 rnm. of N.A. 0'95 ; but in this case it was impossible, even with 

 lenses of a total power of 18 diopters, which is far too powerful, 

 and upsets the objective altogether. 



This application of the additional lens, therefore, I think is of 

 theoretical interest, but hardly of practical value. 



I think that this device of the additional lens is worthy of 

 extended trial, both for the purpose of correcting for the 

 thickness of the cover-glass, and for the conversion of an oil- 

 immersion into a water-immersion. I shall be gratified if it 

 should prove of use to any one in practical work, and should 

 be glad to hear that some one has taken it up. 









Journ. Quekttt Microscopical Club, Ser. 2, Vol. XII., No. 77, November 1915. 





