AMERICAN INSTITUTE. 4lY 



one of the best ever manufactured. It cost, when mounted, nine thousand 

 four hundred and thirty-seven dollars. 



At the Cambridge Observatory there is a telescope that has eightean 

 different powers, ranging from 103 to 2,000. It was made at Munich. 



The Tuscaloosa Observatory has a superior instrument, made by Simms, 

 of London, which has magnifying powers ranging from 44 to 1,640. Cost 

 four thousand dollars. 



Mr. Rutherford, of this city, owns a refracting telescope, made by Henry 

 Fitz, of New York. The aperture of the object glass is nine inches, and 

 its focal length nine and a half feet. It is mounted equatorially, with clock 

 work like the Dorpat telescope made by Gregg and Hupp, of New York. 

 The hour circle is eighteen inches in diameter, and the declination circle 

 eleven inches. It has four eye pieces, the highest magnifying six hundred 

 times. It cost, including clock work and micrometer, two thousand two 

 hundred dollars. It rests upon a brick column, surrounded by a revolving 

 dome twelve feet in diameter. 



Mr. John Campbell has an observatory on the top of his house in New 

 York. The dome is twelve feet in diameter, the opening in which for the 

 instrument is fifteen inches, and extends a little beyond the zenith. It is 

 an achromatic refractor, eight inches aperture, and ten and a half feet 

 focal length. It has six negative eye pieces, magnifying from 60 to 480 

 times. Made by Henry Fitz. 



Mr. Van Arsdale, of New Jersey, has a fine telescope. So has Charles- 

 ton, South Carolina ; Kentucky University, Dartmouth College, Shelby 

 College, Michigan ; Buffalo Observatory, Cloverden Observatory, Hamilton 

 College, and the Dudley Observatory, the telescopes contained in which are 

 all worthy of a description. 



In accordance with a recommendation made by Sir John Herschel, in 

 1854, to the British Asssociation, that daily photographic pictures be taken 

 of the sun's disk, for the purpose of studying by comparison its physical 

 changes, a photographic telescope has been constructed and placed in the 

 Kew Observatory. The proportions of the instrument ai'e as follows : Di- 

 ameter of the object glass, 34 inches, and its focal length 50 inches. The 

 eye glass magnifies 25 times. The object glass is under-connected in 

 such a manner as to produce a practical coincidence of the chemical and 

 visual foci. Other accurate and careful experiments have been made to 

 regulate the light, time of producing the image, and measuring the diame- 

 ter of the spots. 



Mr. Henry Fitz said that he cheerfully complied with the invitation of 

 the Club to speak of telescopes and their construction. The instrument 

 has lately been employed to take photographs of the heavenly bodies. Here 

 are some of the moon, taken lately at Boston. 



Photographs of Jupiter, show his belts imperfectly — perhaps we may do 

 better before long. A Grerman spectacle maker having combined a convex 

 and a concave lens, found that it furnished a superior view of distant objects; 



[Am. Inst.] 27 



