REMARKS ON UNIFORMITY OF NOMENCLATURE 
IN REGARD TO MICROSCOPICAL OBJEC- ~ 
TIVES AND OCULARS. ; 
BY R. H. WARD, M.D.* 
Tue nominal focal length of an achromatic objective, as used 
by microscopists generally, represents its amplifying power as 
actually used in the compound microscope. Even the equivalency 
in amplifying power with a single lens of the same focus is no 
longer distinctly realized, while the size and appearance of the 
combination, its working focus, angular aperture, and microscop- 
ical efficiency, are not even hinted by the figures used. The nom- 
inal focus represents the magnifying power and those properties 
dependent on it. Like other measurements, these must be stated 
by comparison with known standards. To use diverse and u- 
known units of measurement in cases designed to be compared 
with each other is simply self stultification. To call two lenses, 
of identical magnifying power, respectively one-fourth and 
sixth inch lenses, is just as indefensible as to call two hous am 
equal height, forty and fifty feet high respectively. To argue against 
the existing looseness of usage in naming lenses, is only to stale 
what everybody knows in regard to the advantages of uniform stan- 
dards of measurement generally. So impressed are many mic 
pists with the urgency of this question, and so determine 
they to escape from some of the present confusion, that a com 
tee has been appointed to report on the subject. Though that : 
mittee is unprepared to report, it is believed that giving publi 
to some facts and opinions involved in the consideration, may | 
to useful agitation and to increased definiteness of ideas 4 2 
information in regard to it. Of course it would be premature 
i claim or expect accuracy of statement or safety of opinion 
= such a complication of disputed questions; and what is said, 
designed to be contributory and suggestive, and in RO 
dogmatic or final. 
The great variation in objectives of identical name is fa 
bstance of remarks made by the writer at the Indian | È 
faat 4 Aya ray s of Science. 
iat the su 
the American Acsociation 
(136) 
