220 HOW TO SEE WITH THE MICROSCOPE. 



employed, or objectives of narrow apertures used, the 

 entire attachment can be removed if desired. This 

 illuminator, as originally designed, was intended for 

 use with dry objectives and with moderate magnifica- 

 tions ; the idea of using it with immersion glasses of 

 high angles and under high powers, originated with 

 George W. Morehouse, Esq., of Way land, New York, 

 who is well known as an expert and accomplished mi- 

 croscopist. The special advantages obtained by the 

 immersion system in the case in hand are too apparent 

 to need further mention. It will be noticed, too, that 

 the Beck is thus made to do duty like the Wenham 

 reflex in a way quite foreign to the purpose of its 

 original inventor. 



The advantages derived by the use of the instrument 

 are : First, we are thus enabled to view objects by the 

 aid of reflected light; the so-called " opaque illumina- 

 tion," under the highest amplifications and (if the proper 

 objective be employed) with superb definition, as is 

 attested by its unequaled work over the Nobert 19th 

 band ; and by the employment of artificial light, a com- 

 mon kerosene hand-lamp being all that is required. In 

 this respect the instrument stands alone and inimitable. 

 Second, the views given are surface markings only. 

 There is no "penetration" here. The focus must be 

 most accurately drawn, and on the surface of the object. 

 The slightest deviation therefrom is instant and total 

 defeat. Thus we are enabled to locate structure, at 

 times a most valuable assistance to the observer. Third, 

 by a slight change in the position of the lamp, the mir- 



