696 NATURAL HISTORY MISCELLANY. 
to give the effect of snow scenery. As I do not remember to have seen a 
description of the place in print, I send you this note with a specimen of 
the sand forwarded by General Kautz. — GEORGE GIBBS, New York 
MICROSCOPY. 
EW FoRM oF BINOCULAR FOR USE WITH HIGH POWERS OF THE 
Microscopr.* — Of the several forms of binocular arrangement for the 
microscope which et hitherto been constructed, only such as are 
ee. for use with low powers exclusively, have as yet come into gen- 
eral use. Of these, en Wenham prism is the bape m and hardly 
any bd form is employed at all by British or American constructors. 
with 
the field is so imperfectly and so unequally illuminated that it ceases to 
be available. 
he Wenham binocular, like the original binocular of Dr. Riddell, and 
like the different forms constructed by Mr. Nachet, divides the light, 
P i gh 
aaia, With objectives of low power, the base of each conical 
tionable; but with high power objectives, the pencils are very slender; 
and at the distance behind the combination at which it is necessary to 
place the binocular construction, many are very disproportionately di- 
vided, and many escape division altogether. 
By the introduction of an erector into the body of the microscope, the 
l 
years since, constructed a binocular eye-piece which solves completely 
the optical problem under consideration for all powers; but this instru- 
 *Read by F. A. P. Barnard LL. D.. Hán ere = Columbia College, N. Y., before icro- 
scopieal Ameriean Association the Advancement of Science, of aiii 
