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Refractor in double-star observations. Up to this time I have discovered and measured over 100 new pairs, most of them difficult and interesting objects. The list embraces a number of prominent stars : 8 Andromede, 51 Cygni, 47 Tauri, 38 Persei, Aldebaran, etc. Also several of the pairs already known have been found to be triple, as Nos. 17, 171, 366, 2287, 2342, and 2579 of Struve; 09 336, 0x (app.) 220, etc. The larger part of the time has been given to micrometrical measurements of the most difficult of pairs already catalogued, special attention being paid to pairs supposed to be now single, or too close to measure with ordinary apertures; and very unequal pairs and doubles generally, which have not been measured since Struve, or within the last twenty or thirty years. The field in these directions is large, and the results obtained will in the end, I think, be more valuable than measures of the recognized binaries and other familiar objects, certain to be attended to by other ob

I expect to follow up this work vigorously during the coming year. No other use is being made of the telescope. It is admirably adapted to this class of work, and probably superior to any instrument in the world, except the Washington 26-inch. (Signed)

S. W. BURNHAM, Cincinnati Observatory, Mount Lookout, Ohio.

Professor 0. STONE, Director. 1st. Personnel.—There is no regularly paid assistant. The director has been greatly aided, however, by two of his pupils, Messrs. Herbert A. Howe, and Winslow Upton.

20. Instruments. The only large instrument is a Munich Refractor, of 28 centimeters clear aperture. The object-glass of this was refigured, and a new Driving-clock attached in December, 1874, by ALVAN CLARK AND Sons. The observatory is also supplied with a number of subsidiary instruments.

3d. Observations.- Principally the observation of double stars between 0° and 40° south declination. Incidentally a number of new doubles have been detected. A few miscellaneous observations have also been made.

4th. Publications during 1877.—1. Catalogue of New Double Stars discovered by Mr. H. A. Howe. 2. Micrometrical Measurement of Double Stars, made by Professor O. M. Mitchel in 1846–8, at the observatory on Mount Adams. 3. Micrometrical Measurement of Double Stars, made in 1875–6, at Mount Lookout (new observatory).

Pennsylvania College Observatory, Gettysburg, Pa.

Professor Philip M. BIKLÉ, Director. Our observatory is used almost entirely for the general purposes of class-instruction. Like many others, I am so burdened with the duties of teaching that I have little or no time for special work; and even if I had, we are not yet equipped fully enough for pursuing any special investigations. I look forward, however, to some special work in the direction of solar physics.

Our principal instruments are an Equatorial Telescope, with a 6.4inch object-glass, 9 feet focal length; a Transit Instrument, with 2.2inch object-glass and 30 inches focal length; a Negus Break-circuit Chronometer; and meteorological instruments.

Our work has been confined almost entirely to keeping correct time, and to the usual meteorological observations. The only publication during the year was a pamphlet of 36 pp., by myself, on “Our Present Knowledge of the Sun."

Morrison Observatory, Glasgow, Mo.

Professor C. W. PRITCHETT, ector. The Morrison Observatory was founded at my request, in connection with Pritchett School Institute, by Miss Berenice Morrison. She has already donated to the observatory $50,000, and an equal sum to Pritchett School Institute. I am now assisted by my son, Henry S. Pritchett.

The observatory building has an eligible site half a mile east of the college, and was completed in 1876. It has a front on the south of sixty-five feet. On the east is the Equatorial Room, of brick, circular on the inside. The entire dome, twenty-four feet in diameter, is easily revolved by a moderate pressure of the hand on a system of wheel-work. The circular shutters are in four sections, and are readily raised or lowered by a system of gearing, working two pairs of endless chains. The centre of the pier for the Equatorial is twenty inches south of the centre of the dome, so as to bring the centre of motion of the instrument to the centre of the sphere.

The Transit Room—a strong frame building—is directly west of the Equatorial.

The Library and Work Room is directly west of the Transit Room, and is separated from it by a hall.

Instruments.—The Equatorial, by ALVAN CLARK AND Sons, was mounted in December, 1875. The objective is 127 inches in aperture, and focal length 17 feet. It is furnished with Finder, Automatic Movement (very simple and regular), Filar-position Micrometer, and a range of power from 50 to 1200. Its cost in the shop was $6000 in gold. Its performance has proved very satisfactory.

Transit Circle, by TROUGHTON AND SIMMS, of London, was mounted in June, 1877. The objective is 6 inches, and focal length 82 inches. Its style of mounting is similar to that of the new Transit Circle of Harvard College Observatory.

Work of Last Year.-Unfinished as the observatory was, work was done during the year 1876 as follows:

1. Regular time-observations were made.
2. Meteorological records were made three times each day.

3. Many occultations of stars were observed, and applied to the determination of the longitude.

4. Satellites of Saturn (3, 4, 5, 6) were specially observed from September till January.

5. Much work was bestowed on the great nebula in Orion in the latter part of the year.

6. Many close double stars were observed by position-angle and angular distance.

7. Popular observations of the moon, planets, nebulæ, clusters, and double stars were very numerous, to meet the demands of visitors.

The observations on the Equ rial during the present year have been-micrometric measures on close double stars and diameters of planets, and position-angle and distance of satellites. Recently the new satellites of Mars have been often observed. We are also continuing observations on satellites of Saturn. We have published our observations on these satellites.

Arrangements are in progress to determine our longitude by clocksignals with the United States Naval Observatory. Our position, as already approximately determined, is: Lat. 39° 16' 17.5'' N., long. 6h 11m 105 W. of Greenwich.

Private Observatory, Hartford, Conn.

D. W. EDGECOMB, Director. This consists of a small framed building, with revolving dome 12 feet 6 inches in diameter. It contains a Telescope, by ALVAN CLARK AND Sons, with object-glass 9.4 inches clear aperture, mounted equatorially in the best manner. The instrument is used by its owner in general observations of the moon, planets, and double stars, other occupations preventing at present any more systematic work. The object-glass is one of Mr. ALVAN CLARK's latest works, and is of the highest excellence, exhibiting objects generally considered tests for 12 inches.

The outer satellite of Mars was observed on two occasions after the announcement of Professor Hall's discovery. An observation of the bright spot which appeared upon Saturn in December, 1876, was used by Hall in his determination of the rotation period of that planet, and some new double stars have been found with this instrument.

Dr. Henry Draper's Observatory, Hastings-on-Hudson, N. Y.

Dr. HENRY DRAPER, Director. In answer to your letter of inquiry in regard to my observatory at Hastings-on-Hudson—1st. My wife is my assistant. 22. The principal instruments are a Silvered-glass Reflector, of 28 inches aperture, mounted equatorially; an ALVAN CLARK Refractor, of 12 inches aperture, mounted equatorially; a 15-inch Silvered-glass Reflector, mounted as an alt - azimuth; a 2 - inch Transit Instrument; Clock; Chronometer; and Chronograph. 3d. My principal work during the past year has been spectroscopic photography, which has led me to the discovery of oxygen in the sun. 4th. The same line of work will be pursued during the coming year, as the observatory is fitted with a complete electric apparatus for spectrum photography, consisting of an engine, Gramme machine, 18-inch Ruhmkorff coil, etc.

I have published in Silliman's Journal the results of an examination of the astronomical conditions of the atmosphere of the Rocky Mountains, made during the past summer. On the whole, the conclusions are that the steadiness of the telescopic images is less than at New York, while the transparency of the air is much greater at the higber elevations.

Observatory of Yale College, New Haven, Conn.

Professor C. A. Lyman, Director. This observatory is intended chiefly for use as a means of in.. struction in connection with the classes in astronomy taught in the college. There is no endowment for other purposes. During the past year it has been in charge of Mr. H. A. Hazen and Mr. Wm. Beebe.

Instruments.- Equatorial, 81 inches; Altitude and Azimuth Instrument, 4 inches; besides smaller instruments; two Sidereal Clocks and a Sidereal Chronometer; Sextants, etc.

A full series of observations on comets b, c, and f, and a few on e, have been made, and partially published.

Princeton College Observatory, Princeton, N. J.

Professor C. A. YOUNG, Director. The Halstead Observatory, with its magnificent dome (nearly forty feet in diameter), does not at present possess an instrument; but it is hoped that within a short time the deficiency will be supplied.

A small observatory, for purposes of instruction, is just completed after the plans of Professor Young, the funds being supplied for its equipment by the trustees of the estate of the late John C. Green, who founded the School of Science.

The building is of wood, this material being chosen for the purpose of allowing the temperature of the outside and inside air to be rapidly equalized. To prevent danger from fire, all the lights are from fixed gas-jets fitted with Bogart's automatic electrical apparatus for lighting

The dome is 18 feet in diameter, and is provided with a fine Equatorial, by CLARK, of 94 inches aperture and about 12 feet focal length. The Gaussian curves are used in the construction of the object-glass, and the two lenses are so mounted that the distance between them can be adjusted so as to give whatever chromatic correction may best suit the work in hand, whether visual, spectroscopic, or photographic.

The instrument is provided with all the usual micrometric accessories, and with a Single Prism-spectroscope by CLARK, which is also adapted to the use of diffraction gratings. Of these there are three, with lines 14 inches long, the ruled space being 2 inches in width, prepared expressly for this instrument by Mr. CHAPMAN with Mr. Rutherfurd's machine. There is also a powerful compound Spectroscope, by GRUBB, and there are the necessary electrical appliances.

In the meridian three instruments are, or rather are to be, mounted in separate rooms.

The Meridian Circle is in process of construction by Fauti, of Washington. Its telescope will have an aperture of 4 inches, and its circles will be 2 feet in diameter, reading by four microscopes. It will be provided with collimators, reversing apparatus, and apparatus for examination of pivots. It will be mainly on the plan of the instrument at the Harvard College Observatory, and will in all points be a very complete and perfect instrument for purposes of instruction.

In the adjoining room is mounted a “broken ” Transit, by KAHLER, of Washington. It has an aperture of 24 inches, with a focal length of 30 inches; is fitted with a reversing apparatus, with the necessary level and micrometer for latitude determinations, and with a pair of collimators.

In a third room are mounted a small Transit Instrument, of about 14 inches aperture, and a Universal Instrument, with 8-inch circles, by BUFF AND BERGER, of Boston.

In the prime-vertical is mounted the AYСRIGG Transit; of 3 inches aperture and 3 feet focus. It has an iron stand and reversing apparatus, by STACKPOLE, of New York.

At the junction of the two wings a room is formed which contains a lift by which portable instruments may be taken up to the roof, and used upon a platform, which is detached from the building and

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