Journal 



OF THE 



NEW-YORK MICROSCOPICAL SOCIETY. 



Vol. I. MARCH, 1885. No. 3. 



ADDRESS OF THE PRESIDENT, MR. CORNELIUS 



VAN BRUNT, DELIVERED AT THE ANNUAL 



RECEPTION, FEBRUARY 6th, 1885. 



The members of the New- York Microscopical Society have 

 invited their friends to be present this evening, not for the pur- 

 pose of listening to an address, but that they may see the inter- 

 esting and beautiful objects for exhibition under the microscope. 



F^very branch of microscopical research is so full of interest 

 that no justice can be done in any one direction in an address 

 of this character. I will, therefore, confine my remarks to the 

 improvements made in the microscope itself, and to those sub- 

 jects of research that are now receiving the most attention. 



In regard to the instrument : many improvements have been 

 made in the stand, in methods of swinging the understage and 

 mirror, and in adapting the binocular ; — and many of the most 

 decent stands are models of beauty and good workmanship. But, 

 as a whole, the advance has not been as marked in this direction, 

 as in the making of lenses for high magnifying power. A few 

 years since, the only lenses employed were what are termed dry 

 lenses ; that is, an objective brought down close to the object 

 under examination, by means of the rack and pinion, and used 

 without any intervening medium but the air, as an ordinary 

 hand-lens is used. 



With the higher powers, especially, the passage of the rays of 

 light obliquely from the object, through the glass cover, then 

 through the air, and into the lens of the objective, produces a 

 distortion, — as a tea-spoon is apparently distorted by immersion 

 in a glass of water, — the ray being bent by passing from a sub- 

 stance of one refractive index to that of another. 



The first improvement was the use of water as the medium 

 between the glass-cover of the object, and the glass of the ob- 

 jective, instead of air. This arrangement produced a lens ot 



