696. The above cut represents an equatorial telescope manu factured by Mr. Henry Fitz, of New York-the one used by the author in making most of his observations. Its objectglass is six inches in diameter, and its focal length eight feet. It is perfectly achromatic, and performs all the tests laid down. in Dick's Practical Astronomer, as evidence of a good instrument, with perfect ease. Under favorable circumstances, it shows the sixth star in the trapezium of Orion, and to show Polaris double is a very easy test indeed.

A Finder is seen attached to the lower end of the large instrument. It takes in a larger field of view in the heavens than the latter, and enables the observer to look up objects with facility, and bring them into the field of the larger instrument.

THE PHILADELPHIA REFRACTOR.*

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, for copies of several of these cuts from their Monthly Magazine for June, 1856.

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

HAMILTON COLLEGE BEFRACTOR.

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 instrument was made by Messrs. Spencer & Eaton, of Canastota, N. Y., at a cost of $10,000. It is reported to be a very superior telescope, 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?

GREAT REFRACTING TELESCOPE AT CINCINNATI, OHIO.

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 instrumentality it was purchased and mounted.

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

699. Cincinnati refractor-where located? By whom purchased? (Where? Whon? Cost? Size and focal distance?)

700. This superb instrument is mounted in the Daviey Observatory, at Albany, and is one of the most important instruments 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!