Page images
PDF
EPUB
[graphic]

THE SOUTH FRONT OF THE YERKES OBSERVATORY.

BEFORE THE ERECTION OF THE SOUTHEAST DOME.

PUBLICATIONS

OF THE

Astronomical Society of the Pacific.

VOL. IX. SAN FRANCISCO, CAL., DECEMBER 1, 1897.

No. 59.

THE YERKES OBSERVATORY.

BY WILLIAM J. HUSSEY.

The Yerkes Observatory has been dedicated, and its active existence as a scientific institution commenced. On the 21st of October, within the great dome, and in the presence of a large assemblage, the donor, Mr. CHARLES T. YERKES, formally presented the observatory and its great telescope to the University of Chicago, and they were formally accepted for that institution by Mr. MARTIN A. RYERSON, the President of the Board of Trustees.

The dedication of this observatory is an important scientific event of the year, inaugurating, as it does, the work of a great institution devoted to the discovery and teaching of scientific truth, and forming an epoch in its history by separating the period of construction, which has extended over the past five years, from the period of its scientific activity, which is just beginning. The dedication was made the occasion of a large gathering of astronomers and scientific men, and a series of conferences on astronomical and astrophysical subjects, with discussions and laboratory demonstrations of new and interesting phenomena, was held at the observatory during the three days preceding the formal exercises. These exercises were held in the great dome of the observatory on October 21st, and were continued in Chicago the following day. The leading address at the observatory was by Professor JAMES E. KEELER, on "The Importance of Astrophysical Research and the Relation of Astrophysics to other Physical Sciences." Other addresses were made at this time, by Mr. YERKES, in presenting the observatory

to the university; by Mr. RYERSON, in behalf of the Board of Trustees in accepting it, and by President HARPER, in behalf of the faculty. In Chicago, Professors MICHELSON and STRATTON gave brilliant demonstrations with new forms of physical apparatus, having possible applications to the solution of certain pending problems of astronomy. In the afternoon, Professor NEWCOMB delivered his address at Kent Theater, on "Aspects of American Astronomy," and that evening, in conclusion, Mr. YERKES provided a banquet for the visiting scientists.

The Kenwood Observatory and the Yerkes Observatory are so related, that an account of the latter would be incomplete without some mention of the former, and in historical order the former comes first.

The Kenwood Astrophysical Observatory had its beginning in a spectroscopic laboratory, which Professor GEORGE E. HALE erected in Chicago in the spring of 1888. In the winter of 1890-91, extensive additions were made to this, converting it into an observatory proper, with an equipment designed especially for the study of solar phenomena by spectroscopic and photographic methods. The observatory was provided with an equatorial telescope of 12.2 inches aperture. The mounting, which was made by Messrs. WARNER & SWASEY, was large and heavy, and was designed to carry a very large spectroscope. The objective and the spectroscope were made by Mr. BRASHEAR. In connection with the observatory a workshop was fitted up, supplied with such machinery and tools as were necessary for the construction, repair, and modification of apparatus.

Professor HALE was not long in obtaining important results with his new equipment. Early in April, 1891, soon after the telescope had been set up, he succeeded in photographing the spectra of the solar chromosphere and prominences for the first time without an eclipse. Within a year or two, he had discovered new lines in the spectra of the prominences, spots, and faculæ; had obtained photographs of the prominences with the H and K lines and an open slit; had matured his invention of the spectroheliograph and had one constructed by Mr. BRASHEAR, and by its use had secured photographs of all the prominences visible around the entire circumference of the Sun at a single exposure, and then, by a second exposure, had obtained on the same plate the forms of the regions on the Sun's disk, even in its brightest parts, over which the H and K lines are reversed, and had shown that these

forms are identical with the forms of the faculæ obtained by photographs taken in the ordinary way.

At the time of its opening, in the fall of 1892, the University of Chicago was entirely without facilities for research in astronomy and astrophysics. Through the care of Professor HALE and others, the matter received the immediate attention of President HARPER and the Board of Trustees, and in a very short time they had obtained from Mr. YERKES an expression of his willingness to defray the entire cost of a large telescope.

Some years previously a large telescope was planned for the University of Southern California. Large disks of glass for the objective of this instrument were ordered from MANTOIS, of Paris, and, when they were made, were forwarded to the opticians, Messrs. ALVAN CLARK & SONS, Cambridgeport, Mass. This is as far as the matter went. The order to finish the objective never came. In 1892 these disks still remained in the shops of the opticians, and were then for sale. When Mr. YERKES was informed that these large disks of excellent glass could be obtained immediately, he authorized their purchase for the University of Chicago, and entered into a contract with Messrs. ALVAN CLARK & SONS for finishing an objective from them. He also made a contract with Messrs. WARNER & SWASEY for an equatorial mounting for the telescope that bears his name. It thus came about that, within a few weeks from the time his gift was announced, the orders for the objective and for the mounting had been given. Mr. YERKES then wrote to President HARPER: "I have felt it proper that the telescope should have a home, to be paid for by me; and I have concluded to add to my gift an observatory necessary to contain the instrument."

A site for the new observatory was not selected immediately. Professor HALE was chosen Director, and the equipment of the Kenwood Observatory was presented to the University of Chicago, to become a part of the Yerkes Observatory. It appeared to Professor HALE that the exceptional instrumental advantages of the new observatory should not be wasted by a mere duplication of the work done equally well elsewhere, and that the large telescope should not be employed in the observation of objects within easy reach of smaller instruments. Notwithstanding the number of observatories that had been established in various parts of the world, and the importance of the subject, comparatively little attention was being devoted to the phenomena presented by

« PreviousContinue »