Our Present Medical and Students' Microscopes. 75 
class, and to persons who desire information in a concise and con- 
venient form, in regard to the progress thus far made in this 
department of microscopy. While the styles and prices will be 
subject to endless variation, the statements made will be sufficiently 
accurate to form a basis for selection and correspondence for a con- 
siderable time. 
Only standard and available styles are given, by reliable 
American makers, and no such makers have been intentionally 
omitted. The selection of instruments and apparatus of the dif- 
ferent makers is entirely the responsibility of the writer, and not of 
the makers. He has selected such sets, at the makers’ prices, as he 
has been accustomed to recommend to students and others for the 
general purposes of students’ microscopes. 
The Table of Objectives is designed to be complete in regard to 
American lenses, and to present for comparison, and for the con- 
venience of those who desire a variety of lenses by different makers, 
such European items as could be obtained at the time of writing. 
It is believed that the Table will be interesting to others than buyers, 
as showing the prevailing powers, prices, angular apertures, &c., in 
different parts of the world. Notwithstanding the general impres- 
sion that the prices of American objectives are unreasonably high, 
it will be seen that they compare favourably with those of the most 
celebrated English makers. Most opticians prepare, very cheaply, 
mounted objectives of small angle, and usually second quality, which 
answer a good purpose where economy is imperative and difficult 
work is not required. Such lenses are not usually priced and sold 
separately by the American makers, and are therefore not included 
in their columns in the Table of Objectives.* They can be obtained, 
however, at prices proportioned to their angles and quality. The 
prices and angular apertures given in the Table are generally, 
though not in every case, official and up to date ; but a reasonable 
allowance must be made for practical variation from the standard 
angles and powers. There is understood to be a screw -collar 
adjustment for all objectives of over 50° angular aperture, unless 
otherwise stated, though, from want of sufficiently distinct descrip- 
tion by their makers, this rule cannot be applied to some of the 
English lenses of medium power and small angle. To persons 
without great experience in microscopy, the best “ test ” of an 
objective is the respectability of its maker. 
The binocular microscope, though not especially applicable to 
medical microscopy, is of such general usefulness that it should be 
preferred in all cases where its price is not a positive objection. 
Binoculars are furnished, when ordered, even by those makers who 
do not manufacture them. 
* This remark would also apply to a few of tlie English opticians. 
G 
VOL. VIII. 
