NATURAL HISTORY MISCELLANY. 627 
underrate his lenses in the naming of them, ay point — presented 
was, that lenses of such low power should do so much, there not be- 
ing any great liability of material difference E the enini present , 
in a of such low power as 38-inch. No measurement of its power 
was give Not so, however, in the case of the 4-10, for as is well known, 
and as Mr. Bicknell states, objectives of various makers rating the same, 
differ greatly in their magnifying power. And this again occurs, not only 
with the objectives of different makers, but even the objectives of the 
same maker differ, although rated the same, e. g. in R. & I. Beck's Cata- 
logue, 1868, are advertised 1-4 inch objective (No. 234) magnifying power 
two hundred and ten, and on a succeeding page 1-4 inch objectives (No. 
296) magnifying power one hundred and forty diameters. "Therefore I 
lacie’ f London, of Hartnack deg n of Tolles and Grunow of this 
dea or of Gundlach of Vienna, various objectives of each and all of 
which makers I have examined, have either I myself, or other microscop-. 
ists of my acquaintance, been able to effect this.” 
Ido not say with a 4-10 objective, for firstly, they all differ in their 
amounts of amplification, and secondly, neither Hartnack nor Gundlach 
thus denominate their objectives, but as usual with Continental makers, 
number them as 1, 2, 3, and so on. The word power, however, I thought 
could not be ee di: such equality of power being most — 
attained by the use of the draw-tube. 
That an objective ee two — and ten diameters ils 
used in connection with a No. 1 or an A eye-piece, should resolve the 
Pleurosigna angulatum, mounted, not grs but in balsam, and by direct 
light, instead of oblique, is what I wished to put on record, and such I 
think the generality of microscopists would infer on perusal of the arti- 
cle. As, however, Mr. Editor, Mr. Bicknell is of the opinion that I have 
current, I would state that not only have I myself remeasured the ampli- 
fication present on the use of said objective in said resolution, but that I 
am permitted to use the names of Dr. Edward Curtis, formerly of the 
Army Medical Museum, Washington, D. C.; of Mr. Joseph vik Ward, the 
well known microscopist of this city; and of Mr. O. G. Mason, Photog- 
rapher of Bellevue Hospital, names familiar to all mieroseopists in New 
. York, in testimony of the correctness of said measuremen 
As regards the second point raised, namely, the Bionic of object- 
ives by their various makers, it is, undoubtedly, the fact, not however 
I think from any intention to mislead, but rather from an inherent want. 
or defect in the nomenclature in use. The denominating of an objective 
a 4-10, 1-5, 1-8 and so on, answers a certain purpose of informing us of 
about what power is meant, but if, in addition, the makers would engrave 
