Microscopy at the American Exhibition. By R. H. Ward. 29 
tube with the addition of a pin moving in an oblique slot and 
giving a rapid and very steady and safe adjustment by means of a 
screwing movement, and an iris diaphragm capable of being used 
after the Continental plan close to the object slide, consisting of a 
thin split tube whose blades are overlapped and gradually closed by 
being screwed up into a dome-shaped cavity in the bottom of the 
stage plate. The instrument is furnished with Wale’s excellent 
lenses. 
James W. Queen and Co. exhibit their instruments, which are 
of the English type, reduced and adapted to the student’s microscope 
grade, and aim rather to combine well-known excellences into a 
good and popular instrument, than to introduce novelties of con- 
struction. 
The instruments by W. Y. McAllister, in the Pennsylvania 
State Educational Exhibit, do not seem to suggest any of the pro- 
gress of recent years. 
A set of William Wale’s exquisite lenses was exhibited by 
Mr. Zentmayer, but was unfortunately allowed to be prematurely 
removed from the case. 
Several makers are conspicuous by their absence. All visitors 
to this department would have been glad to see Hartnack, and 
Powell and Lealand, and the German makers, well represented ; 
and many felt disappointed at the absence of Spencer, of Tolles, 
and of Grunow, having very reasonably expected that such promi- 
nent American makers would, from motives of fitness and courtesy, 
if not of interest, contribute their share to the completeness of the 
International Exhibition. It would have been peculiarly appro- 
priate, in view of their undisputed excellence and their high claims, 
that the new duplex-front objectives of Tolles should have been 
placed in comparison with the world’s other lenses, while the 
unhandsome insinuation which is being extensively printed in 
advertisements, that they are not at the exhibition because they 
would not be properly examined there, must have been authorized 
without serious thought by the persons responsible for it. It is 
well known that President F. A. P. Barnard, who was associated 
with such judges in this group as Professors Joseph Henry, 
J. E. Hilgard, and others scarcely less distinguished, gave his 
personal attention to the examination of the exhibits in this de- 
partment. 
Among the objects, other than microscopes, of special interest 
to microscopists, may be classed the double-stained vegetable pre- 
parations by Dr. Beatty, the large series of fine mounted objects by 
W. H. Walmsley, and the far from equal set of imported objects, 
both exhibited by James W. Queen and Co., and the more limited 
series of pathological specimens, by Dr. H. N. Krasinski, in the 
Russian department; the already famous machine for micro-ruling 
