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697. This instrument is located in the Observatory of the High School of Philadelphia. Its focal length is eight feet, and its aperture six inches-the same as the one on the preceding page. It was made by Merz & Mahler, of Munich, and cost $2,200.

* We are indebted to the courtesy of Messrs. Harper Brothers, of New York, fa: copies of several of these cuts from their Monthly Magazine for June, 185€.

C97 The Philadelphia refractor? Size? By whom made? Cost?



698. This instrument has a focal length of sixteen feet, with an object-glass thirteen-and-a-half inches in diameter. Its focal length is therefore about four feet less than is usual in the Munich instruments of the same aperture. The flint and crown glass discs for it were imported from Germany, and the instru ment was made by Messrs. Spencer & Eaton, of Canastota, N. Y., at a cost of $10,000. It is reported to be a very superior tele scope, and, in workmanship, is regarded as fully equal to the Munich instruments.

698. Size of the Hamilton Ccliege telescope? What peculiarity as to length! By whom made? Cost?


699. The above cut represents one of the best telescopes in the United States. It is located in the observatory on Mount Adams, near Cincinnati, Ohio, and was for several years under the direction of the late Prof. O. M. Mitchel, by whose instru mentality it was purchased and mounted.

The object-glass is about 12 inches in diameter, with a focal distance of 17 feet. 1: as purchased in Munich, Germany, in 1844, at an expense of nearly ten thousan dulars.

699 Cincinnati refractor-where located? By whom purchased? (Where? When? Cust? Size and focal distance?)

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700, This superb instrument is mounted in the Dudley Ob servatory, at Albany, and is one of the most important instru ments in America. Its focal length is 15 feet 2 inches. The object-glass, made by the late Henry Fitz, of New York, is 13 inches clear aperture, and the tube is of mahogany, constructed by glueing together strips of about an inch in width. A finder, or small telescope for finding objects, is seen attached to the lower end of the large instrument.

700. Where located? Size? By whom made? What said of tube? Finder!

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701. This is probably the best ins 1ument in the United Staten Its object-glass is 15 inches in diam ter, with a focal length of 22 feet 6 inches. It has eighteen different powers, ranging from 103 to 2,000. It was made by Merz & Mahler, of Munich, Bararia, and cost $19,842.

The cut shows the opening in the revolving dome of the observatory, and the cbserve in his chair at the eye-piece.


701. Comparative value? Size Magnifying powers? By whom made? Cost of

inst umont?

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