os Ue Oe 
NEw SERIES. 
SINGLE CoPiEs, 15 CTs. 
VoL. X. No. 257. FRIDAY, DECEMBER if; 1899. ANNUAL SUBSCRIPTION, $5.00 
<s, WM. GAERTNER & CO. 
> SS 
Astronomical and Physical Apparatus 
152-158 EAST 56TH ST., CHICAGO 
SPECIALTIES 
STANDARD APPARATUS OF NEW AND IMPROVED DESIGNS 
READING MICROSCOPES AND TELESCOPES 
ASTRONOMICAL TELESCOPES HELIOSTATS 
SPECTROSCOPES DiviIDING ENGINES, COMPARATORS 
MICHELSON INTERFEROMETERS GENERAL LABORATORY APPARATUS 
BOLOMETERS a UNIVERSAL LABORATORY SUPPORTS 
MINIATURE INCANDESCENT LAMPS. 
MINIATURE LAMP RECEPTACLES. 
X-RAY TUBES AND APPARATUS. 
FLUOROSCOPES. 
Catalogues on Application. 
Kdison Decorative and Miniature Lamp Department, 
(GENERAL ELECTRIC ComPanr,) 
HARRISON, WN. J. 
e Having recently purchased all of the best crystals taken from the 
Celestite. noted ‘‘Strontian Cave’’ at Put-in-Bay, Ohio, we can offer these at 
much less prices than crystals of like quality have before been sold. 
The better ones range from 5 to 7 inches in diameter, with magnificent terminations. These are from 
$5 to $8 each. Crystals from 3 to 5 inches in diameter, $1 to $5 each. Smaller crystals, good 
terminations, 5 cents to 50 cents. ; 
WARD'S NATURAL SCIENCE ESTABLISHMENT, 30 to 40 College Ave., Rochester, N.Y. 
Pamphlet No. 315 (just issued ) re- 
N W. AF I ARA US fers to a lot of Electrical Measur- 
: Mis i ing Instruments and Psychologica] 
at Special Prices. Apparatus made by Willyoung & 
Co. When Leeds & Co. purchased the manufacturing plant, etc., of the old firm, these goods were 
included in the sale, and now as sole agent for Leeds & Co., I am authorized to quote prices that 
would be entirely impossible under other circumstances. 
The present opportunity is one of a life time to buy New Scientific Apparatus at figures 
that would be appropriate for second-hand or behind-the-times appliances. 
Tf int ted, don’t fail t 
siritel ah Gree foe a oe of JAMES G. BIDDLE 
N66 345.77 1034 Drexel Building, Philadelphia 
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