RECONNOITERING TELESCOPES. 



John Davis, Mathematical Instrument Maker, Derby, England, 

 begs to call the attention of the Military and other gentlemen to 

 these celebrated Instruments, } which measure when closed only 3£ 

 inches, but which possess sufficient power to show clearly Jupiter's 

 satellites, — packed in a strong case, price 355. To the same Tel- 

 escope can be had an Astronomical Eye-Piece and Clip-Stand, with 

 which auxiliaries Saturn's ring is distinctly defined* The whole 

 packed in a neat oblong case 4£ inches by 3 inches. Price com- 

 plete £3. 



A variety of Achrometic Objectives for Microscopes of the first 

 character. Price varying from £2 5s to £3 5$., depending on 

 their focus. 



10-inch Gravatt Levels complete, £15 15s., without Staves 2 



guineas less* 



July, 1844. 









Dr. J. R. CHILTON, 



PRACTICAL CHEMIST, &c, 



No. 263 Broadway, New York, 



* 



Keeps constantly for sale at his establishment, a general assort- 

 ment of Philosophical and Chemical Apparatus, Chemical Prepara- 

 tions, and every thing necessary for the study of Chemistry and 

 other branches of Natural Philosophy 

 lowing : 



Pixn's French Air-pumps, with glass barrels ; other air- 

 pumps with brass barrels, single and double, of various 

 gether with the various apparatus used with them. 



among which are the fol- 



■ 



Large and 



small Plate Ele 



sizes, 



to- 



Machines, Cylinder 



Electrical Machines, and a variety of Electrical Apparatus. 

 Electro-Magnets, mounted on frames, of various sizes, capa- 

 ble of supporting from 20 to 3000 lbs. 



Page's Compound Magnet and Electrotome, for producing 

 brilliant sparks and powerful shocks. The same instrument, with a 

 contrivance attached by which the intensity of the shocks can be 

 modified at pleasure, which renders it one of the most convenient 

 instruments for the application of electricity as a remedial agent in 

 the cure of disease, and for physiological experiments. 



Small working models of Electro-Magnetic Machines, of) 

 d.fferent kinds, and a great variety of Electro-Magnetic Instru- 

 ments for the purpose of illustrating the theory of Electro-Mag- 



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