Microscopes at the American Exhibition. Bij J. G. Hunt. 27 
nature, and when these are shown without optical distortion, we 
realize that splendour and grace are the common garments of all. 
American objectives are not behind the best from abroad. I 
shall speak chiefly of those made by Mr. Tolies, because others of 
home product which I have seen have been disappointing. It is 
more difficult to judge of Mr. Tolies’ work than of that of any other 
optician, because no two of his lenses that I have seen are alike ; 
and that dissimilarity is evidently designed, and not accidental. 
Most surely his guide is not Lister, nor Amici, nor Abbe ; but his 
genius is more comprehensive than all these combined. The true 
optician is he who can vary his formula at will to obtain other or 
finer results. To work by rule is mechanical, and may be taught 
an apprentice ; it is never marked by progressive excellence. The 
power to direct your steps at will, while threading the labyrinth 
of optical construction, marks the master. That Mr. Tolies can 
do. In him are greater optical possibilities in the construction of 
lenses for the microscope than in any other maker, and my judg- 
ment is based solely on work. Still I have seen many lenses of his 
make which disappointed me greatly, because to gain some special 
point other qualities which I happened to value most were sacri- 
ficed. But when I detected, by larger experience, that all this 
was designed, and not accidental, my appreciation increased. 
It is more amusing than instructive to hear learned professors 
define the limit of microscopical vision and the angle of aperture 
of objectives. They gravely tell us moreover that penetration and 
resolution are incompatible qualities in lenses. Possibly, in a 
degree, they may be so, hut that degree is not yet a matter of pro- 
fessional experience. I can indicate objectives of Mr. Tolies’ make 
of extreme angle, yet their penetration is so extraordinary, that 
they form the best lenses I know for best histological work by 
central light, showing details with a brilliancy which I never saw 
otherwise. A recent T \, th which came into the world not by oblique 
presentation exclusively, is the highest standard to which I can 
refer. It is high commendation to compare any lens with Powell 
and Lealand’s new 1th, but Mr. Tolies’ last T \yth is superior in most 
respects. Alike in power, the English lens has a remnant of 
London fog in its construction : the Boston one is brilliant and 
clear as crystal. Moreover, the Boston glass shows clearly struc- 
tural details beyond the penetration of the English lens, without 
change of focus. Both are used wet or dry. The 1th has a separate 
front, the Toth is set for dry work by adjusting the screw-collar ; this 
plan is more convenient than the separate front. A recent 1th, 
bearing the name of Spencer, from whom we naturally expect much, 
gave results not elsewhere obtained in lenses of that grade and 
cost — student’s objective at $20 ' 00 — hut it was triumphantly 
under-corrected, and all ablaze with orange light. 
