1885.] NEW-YORK MICROSCOPICAL SOCIETY. 23 



nearer to the latter than to the former. Now, as direct sunlight 

 is not suitable for opaque objects, since by diffraction it confuses 

 their structure by creating deceptive appearances, so the electric 

 light is, in my opinion, objectionable in the ratio of the nearness 

 of its intensity to that of direct sunlight. For the study of 

 opaque objects under low-power objectives, 1 find lamp light to 

 be the best, its character as a more diffused light fitting it for 

 the coarser kinds of work, such as the exhibition of elytra. In 

 the examination of such transparent objects as require high- 

 power objectives, the electric light is undoubtedly the more 

 effective. The point which I wish to make is, that no single kind 

 of artificial light has sufificient versatility for the best perform- 

 ance of every one of the many and diverse varieties of work to 

 which the microscope is applied." 



Dr. F. Y. Clark : " At first I doubted the serviceableness of 

 the electric light in microscopy. But when by means of it I found 

 myself able to distinguish good, velvety gold foil from poor foil, 

 then I began to prize it. In poor foil are minute holes and frac- 

 tures, from which the good foil is free. These are detected by 

 the electric light, while the light from an oil lamp does not dis- 

 close them." 



Mr. P. H. Dudley : " As the result of eight months' trial of the 

 electric light in photomicrography, I found that success demands 

 the employment of a short, thick carbon filament, and the heat- 

 ing of the filament to a degree of incandescence that is scarcely 

 below the destructive point. If the heat go a degree or two 

 higher, the lamp is destroyed. I used the bichromate battery, 

 of eight cells, with double plates, seven inches by eight, in each 

 cell. Apart from considerations of expense, and the extreme 

 difficulty of securing an even current of the requisite strength, 

 the electric light is the best for photography. These drawbacks, 

 however, led me to abandon its use." 



The President : " The work of applying the electric light to 

 the microscope is yet in its infancy. What form of lamp is best 

 for general use has not, perhaps, been determined. Probably 

 several forms will be required, to suit different purposes. Only 

 by the skill and industry of many men can the problem be solved. 

 The electric light is of pure and excellent quality. But, in prac- 

 tice, the height to which its brilliancy can be carried, is limited. 

 For I have found that as soon as the light has reached perfect 



