The Encyclopedia Americana (1920)/Lick Observatory

LICK OBSERVATORY, astronomical department of the University of California. James Lick (q.v.), by deeds made in 1874 and 1875, charged a board of trustees to expend the sum of $700,000 for the purpose of purchasing land ana constructng “a telescope superior to and more powerful than any telescope yet made . . . and also a suitable observatory . . to be made useful in promoting science.” Under the provisions of this deed a site was selected in 1876 on the summit of Mount Hamilton about 26 miles, by road, from San José, Cal. The land (about 3,000 acres) was granted at various times by the United States and by the State of California.

Astronomical observations of precision and delicacy require a steady atmosphere as well as a very transparent one, and the site chosen is favorable in both respects. This was thoroughly tested in 1879 by Prof. S. W. Burnham before any buildings were erected. The first board of trustees (D. O. Mills, president) chose as chief advisers Profs. Simon Newcomb and Edward S. Holden, and appointed Professor Holden as director. In October 1874 the latter submitted a plan for the building of the observatory and a program of work, which were accepted by the trustees, according to which the buildings were constructed and the work carried on from 1874 to 1897. The county of Santa Clara built a fine mountain road to the summit, in 1876, at a cost of $78,000. The work of construction was begun in 1880 by the third board of trustees (Capt. R. S. Floyd, president) with Thomas Fraser as superintendent. To obtain a level platform for the observatory 70,000 tons of rock were blasted from the summit. The instruments were ordered from specifications by Dr. Holden, except the object-glass of the great telescope. After a series of experiments Professor Newcomb advised the construction of a refracting telescope for the main instrument of the observatory. The glass discs were founded by Feil and Mantois of Paris and figured by Alvan G. Clark. The finished objective is 36 inches in diameter, and has a focal length of 56 feet 2 inches. Besides the visual objective, there is a third lens of 33 inches aperture. When this is placed in front of the visual objective the combination becomes a photographic object-glass of 570 inches focal length (the diameter of the photographic image of the moon is about 5.2 inches). The cost of the visual objective was $50,000, of the photographic corrector about $13,000, and of the mounting of the telescope about $45,000. The cost of the dome complete was about $85,000; of the whole observatory about $610,000. The mounting of the great telescope was made by Warner and Swasey, of Cleveland. The whole weight of iron pier and mounting is about 37 tons. The moving parts of the latter weigh about seven tons; the tube weighs nearly three tons. The telescope is used for visual purposes, and micrometer measurements; it is also used for photographic and for spectroscopic observations. Its steel dome is 75 feet in diameter, and weighs 100 tons. It was built by the Union Iron Works of San Francisco. The floor of the dome is movable vertically (about 16½ feet), according to a plan by Sir Howard Grubb, which ensures a convenient position for the observer, no matter whether the telescope is pointing horizontally or vertically. Other instruments are a 12-inch and a 6-inch refractor, a 4-inch comet-seeker, a 6-inch meridian-circle, a 5-inch photographic telescope, a 4-inch transit, a 5-inch photoheliograph, etc.

The great telescope has been in constant use since its erection, and its optical quality has been proved to be excellent. The admirable design and construction of its mounting and dome have much facilitated its work. In 1895 Edward Crossley, M.P., of Halifax, England, presented to the observatory his 3-foot reflector, which has been a powerful auxiliary to the great refractor. The observatory constitutes the Lick Astronomical Department of the University of California. Its staff has comprised many noted observers: Messrs. Burnham, Barnard, Schaeberle, Tucker, Perrine, Hussey, Aitken, Wright and others.

The observatory was one of the very first to be located on a site specially chosen for its adaptation to astronomical work, and its success has had an important effect upon the science of practical astronomy. No one would now think of locating a great observatory without careful consideration of the site to be occupied. The mountain observatories of the world owe much to the experiments made at Mount Hamilton.

The principal objects of research have been: The visual and photographic observation of planets and satellites; the fifth satellite of Jupiter was discovered here by Barnard in 1892. A systematic search for comets has been kept up and 14 unexpected comets have been discovered — Barnard (3), Perrine (9), Coddington (1), besides a comet discovered by Schaeberle uring his observations of the solar eclipse in Chile. Many periodic comets have also been detected and observed. The orbits of new comets have always been promptly computed at the observatory and ephemerides sent out to other stations. Four asteroids were discovered by Coddington in 1898-99. Meteors have been observed and photographed, and their orbits calculated. Double stars have been assiduously observed and many new discoveries made by Burnham, Hussey and Aitken; the orbits of a considerable number of binaries have been calculated. Observations of the zodiacal light and of the aurora have been made by Barnard and others. Successful expeditions have been sent to observe all total solar eclipses since 1888, and very much has been added to our knowledge of solar physics in this way. The transit of Venus of 1882 and three transits of Mercury have been observed and photographed here. The positions of a large number of fixed stars have been determined with great precision by Tucker. Many photographs of the sun and moon have been made. The negatives of the moon have been utilized in the preparation of an atlas of the moon (scale 10 feet to the moon's diameter) by Professor Weinek, and on a scale of three feet by Messrs. Holden and Colton. A great number of important photographs of the milky way were made here by Professor Barnard and others, and of comets and nebulæ by Keeler, Hussey, Perrine and others. A complete outfit of seismometers for recording the intensity of earthquake shocks was installed at the observatory in 1888, and it was supplemented by similar instruments at Berkeley and at other points in California and Nevada, which regularly report to Mount Hamilton. In this way the elements for seismometric record for the State were collected and regularly published. At the same time a list of all recorded shocks on the Pacific coast since 1769 was compiled and discussed by Dr. Holden. Spectroscopic observations of nebulæ, new stars, comets, stars and planets haye been made in great number and with previously unattained precision by Messrs. Keeler, Campbell, Wright, Perrine and others.

The chief problem of the great telescope is to determine the motion of the solar system by spectroscopic observations. The photography of stellar spectra was proposed in the plan of 1874 and attacked in 1888, and it has been followed with marked success, especially in the hands of Professor Campbell. Since 1896 more than 2,000 negatives of stellar spectra have been secured. A preliminary discussion by Campbell leads to the result that the solar system is moving toward a point in 277° R. A. and 20° N. D., at a speed of 19.89 kilometers (12.35 miles) per second. An expedition was sent (at the expense of D. O. Mills) to the southern hemisphere in 1903 to extend this research to southern stars.

The observatory publishes a series of octavo ‘Contributions’ (No. 1 in 1889, No. 5 in 1895), of quarto ‘Publications’ (1887 et seq.) and a quarto Bulletin since 1901 — a journal. The Astronomical Society of the Pacific, founded by Professor Holden in 1889, has close relations with the observatory, and has printed 15 octavo volumes. Visitors are freely admitted to the observatory in the day time to the number of 5,000 or more annually. On Saturday evenings visitors are admitted to look through the telescopes, and as many as 150 to 200 are frequently registered. In this way the observatory has rendered important services to popular education.