104 : 
PRICE LIST. 
Apparatus for viewing Fraunhofer’s fixed dark lines in the 
solar spectrum, consisting of small achromatic telescope 
on stand, with flint glass prism and apparatus to mount the 
same before the objective, and a screen with flue slit, . $35.00 
Apparatus for Fraunhofer’s, Fresnel’s, Herschell’s and 
Schwerd’s experiments on diffraction, .... 60.00 
Wollaston’s camera lucida, mounted for draftsmen, with 
clamp and the necessary adjustments, &c., from . . 10-18.00 
Wollaston’s goniometer, with telescope, graduated circle 5 
inches diameter, the vernier gives the angles to singlfe 
minutes, 40.00 
Same, graduated circle 6 inches, with telescope and improved 
arrangement for holding and adjusting the crystals, . 60.00 
Photometer, constructed by J. & W. G., ... 60.00 
This instrument was made first for Prof. Silliman, Jr. It is ex- 
tremely sensitive, and the results of observations made with its 
aid are of a degree of accuracy and reliability which, we believe, 
has never before been obtained by a photometer. 
Dichroscopic lens, for discovering dichroism in crystals, . 6.00 
Pocket achromatic simple microscope, for the use of bota- 
nists, mineralogists, and others, magnifying from 15 to 25 
times linear, ......... 6-8.00 
Goniometer for measuring the angles of larger crystals, 
(Gambey’s construction.) This instrument may also be 
used for ascertaining the refractive power of prisms and 
crystals, 60.00 
Norremberg’s polariscope, . . . . . . 80.00 
Stauroscope, invented by Prof. V. Kobell, of Munich, . 25.00 
Biot’s polariscope, mounted on tripod and column, and with 
graduated circles, ........ 40.00 
Soieil’s apparatus for measuring the angles of the axes in bi- 
axial crystals, and the diameter of the colored rings, . 60.00 
Soieil’s sacharimeter, ....... 90.00 
Apparatus for showing the transient polarizing structure of 
glass plates by unequal heating, ..... 2.00 
Apparatus for producing the polarizing structure by bending, 4.00 
Apparatus for producing the same by compression, . . 3.00 
Nicol’s prisms, according to the size, from .... 4-10.00 
WE ALSO KEEP FOR SALE 
Raspail’s Simple Dissecting Microscopes, with three lenses, . . $12.00 
Glass slips for mounting Microscopic preparations, per dozen, . . 
Square covers of thin glass, per dozen, ...... .26 
Round covers of thin glass, per dozen, ...... .36 
Microscopic specimens at various prices. 
