The Harvard Astronomical Observatory.

From an advanced copy of the annual report of the Harvard Astronomical Observatory, some detail in regard to the work and needs of the Observatory are published.

During the past year courses in scientific research under the direction of Edward C. Pickering, L. L. D., have been carried on with encouraging results. This is the primary object of the institution and elementary instruction is not given. At present there are about forty assistants engaged in the work, and excellent facilities are offered for study in nearly all branches of astronomy. The observatory is especially fortunate in its opportunities for photographing the stars, the arrangements being superior to those of any other institution.

The largest telescope is 15 inches in diameter and has a magnifying power of 5,000 times. Besides this there are many smaller ones, which are used whenever the night is sufficiently clear.

Early in 1891 a station was established by Professor Wm. H. Pickering at Arequipa in Peru, thus furnishing means for observing and photographing the stars of the southern sky. This gave Harvard a singular advantage over other observatories, for in the wonderfully clear condition of the skies in that quarter, observations can be made nearly all the year round, and are limited only by the size and power of the instruments. Last year 1224 photographs of the southern stars were taken, and from these much valuable information was obtained. The negatives were sent to Cambridge and are now stored with other valuable collections which have been made from the observatory at Cambridge. These latter observations have been taken photometrically and micrometrically, requiring constant use of the instruments. Nearly 4,000 photographs have been made, embracing the spectra of all the stars visible in Cambridge. Among the collection are a series of negatives, representing the condition of the sky for the past six years, and they are supposed to be the most complete set that exists. The six-inch telescope has been used for observing the variable stars and investigating photometric methods of observation. From the photographs taken in Peru it has been discovered that eight variable stars, in addition to the thirty previously noticed ones, have hydrogen lines, bright in their spectra, and by this property, five new variable stars have been discovered. The number of stars of the fifth type, having bright lines in their spectra, like those discovered by Wolf and Rayet, has been increased by nine. Of the thirty seven of the kind, twenty-seven have been discovered from the Harvard Observatory.

The southern hemisphere has never been examined through a very powerful instrument. The cost of an instrument fitted for such work is estimated at about $50,000, and until this sum is donated, the work in this quarter must be limited. The results of these years of experiment and research are stored in a wooden building, liable at any time to be destroyed by fire. The need of a fire-proof building to insure the preservation of the valuable collection is very urgent, and as over $7,000 has already been subscribed it is hoped that a suitable structure may be begun early this year.

The observatory possesses an extensive library on astronomical subjects, which is being rapidly increased from outside sources as well as from its own publications, which have been numerous during the past year.