628 NATURAL HISTORY MISCELLANY. 
upon their objectives the amplification present when the image formed by 
such objective is thrown upon a screen at the recognized normal distance 
.of ten inches (or 254 millimeters) from the object we should then have 
something de e hich I find most convenient for obtain- 
ing this amplification of the objective considered in and by itself is as 
E a f the lines or di ns of a stage micrometer is 
—the collective or field glass of the same having been previously removed. 
The plane or distance from the stage micrometer at which the eye-piece 
micrometer should be placed, namely, ten inches, may easily be effected 
by means of the draw tube. By comparison of the lines of the stage mi- 
crometer as thus Projected, with those of the eye-piece micrometer the 
eye-piece enlarging both sets of lines equally, decer SEAS the 
reading. In this use of the eye-piece micrometer i ary t 
the exact value of its scale should be known, a gt erer when 
otherwise used. The scales upon the micrometers which I use and find 
in general best adapted to the purpose, are a millimetre divided into 1-100 
for the stage micrometer, sunt a centimetre divided into 1-100 for the 
ocular or eye-piece microme 
With the highest respect sak kindliest of feelings towards Mr. Bicknell, 
who has contributed so largely to the advancement of microscopic sci- 
ence in America, I intended in my original communication, not the bring- 
ing before the public the superior boc cu of Mr. Wales' lenses, for 
their merit in this country we are all agreed, but to place on recor 
Mags resolutions as attained by itane low amplification. — J. J. 
HiGGiNS, M. 
T PLEST FORM OF MICRO-TELESCOPE. — At a fleld meeting of tlie 
Fire ose, held in Hoosic Falls, on the 24th of September, Dr. 
H. Ward of , N. Y., exhibited a simpler form of micro-telescope 
than has wikci-eo d boni proposed. He screws an ordinary 4-inch objective 
(5-8 inch wide, 2 3-4 inches solar focus) into an adapter (about 2 inches 
acts as an erecting ej c gii, as in Tolle queue and Curtis' micro- 
light of a 1-inch opening; but the new arrangement gives a really useful 
field-telescope without re quiring a single addition to the microscopist’s 
apparatus. Solid (single pras oce objectives act best as erectors iu 
this case, but the ordinary objectives, from 2-inch to 1-2-inch, answer 
very well. The same arrangement, by raising the tube [pica and 
perhaps substituting a 1-inch objective for the 4-inch. furnishes an erect- 
ing compound microscope which is excellent as a hand-magnifler p fleld 
use; and by removing the lens below the stage we have the ordinary fleld 
microscope on which the object may be placed in the * clinical compres- 
sor,” or otherwise. 
