The Encyclopedia Americana (1920)/Lick Observatory

LICK OBSERVATORY, astronomicaldepartment of the University of California.James Lick (q.v.), by deeds made in 1874 and1875, charged a board of trustees to expend thesum of $700,000 for the purpose of purchasingland ana constructng “a telescope superior toand more powerful than any telescope yetmade . . . and also a suitable observatory . .to be made useful in promoting science.”Under the provisions of this deed a site wasselected in 1876 on the summit of Mount Hamiltonabout 26 miles, by road, from San José,Cal. The land (about 3,000 acres) was grantedat various times by the United States and bythe State of California.

Astronomical observations of precision anddelicacy require a steady atmosphere as well asa very transparent one, and the site chosen isfavorable in both respects. This was thoroughlytested in 1879 by Prof. S. W. Burnham beforeany buildings were erected. The first boardof trustees (D. O. Mills, president) chose aschief advisers Profs. Simon Newcomb andEdward S. Holden, and appointed ProfessorHolden as director. In October 1874 the lattersubmitted a plan for the building of theobservatory and a program of work, whichwere accepted by the trustees, according towhich the buildings were constructed and thework carried on from 1874 to 1897. The countyof Santa Clara built a fine mountain road tothe summit, in 1876, at a cost of $78,000. Thework of construction was begun in 1880 by thethird board of trustees (Capt. R. S. Floyd,president) with Thomas Fraser as superintendent.To obtain a level platform for theobservatory 70,000 tons of rock were blasted fromthe summit. The instruments were orderedfrom specifications by Dr. Holden, except theobject-glass of the great telescope. After aseries of experiments Professor Newcombadvised the construction of a refracting telescopefor the main instrument of the observatory.The glass discs were founded by Feil andMantois of Paris and figured by Alvan G.Clark. The finished objective is 36 inches indiameter, and has a focal length of 56 feet2 inches. Besides the visual objective, thereis a third lens of 33 inches aperture. Whenthis is placed in front of the visual objectivethe combination becomes a photographicobject-glass of 570 inches focal length (thediameter of the photographic image of the moonis about 5.2 inches). The cost of the visualobjective was $50,000, of the photographiccorrector about $13,000, and of the mounting ofthe telescope about $45,000. The cost of thedome complete was about $85,000; of the wholeobservatory about $610,000. The mounting ofthe great telescope was made by Warner andSwasey, of Cleveland. The whole weight ofiron pier and mounting is about 37 tons. Themoving parts of the latter weigh about seventons; the tube weighs nearly three tons. Thetelescope is used for visual purposes, andmicrometer measurements; it is also used forphotographic and for spectroscopic observations.Its steel dome is 75 feet in diameter,and weighs 100 tons. It was built by the UnionIron Works of San Francisco. The floor ofthe dome is movable vertically (about 16½feet), according to a plan by Sir HowardGrubb, which ensures a convenient position forthe observer, no matter whether the telescopeis pointing horizontally or vertically. Otherinstruments 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 usesince its erection, and its optical quality hasbeen proved to be excellent. The admirabledesign and construction of its mounting anddome have much facilitated its work. In 1895Edward Crossley, M.P., of Halifax, England,presented to the observatory his 3-foot reflector,which has been a powerful auxiliary to thegreat refractor. The observatory constitutesthe Lick Astronomical Department of theUniversity of California. Its staff has comprisedmany noted observers: Messrs. Burnham,Barnard, Schaeberle, Tucker, Perrine, Hussey,Aitken, Wright and others.

The observatory was one of the very firstto be located on a site specially chosen for itsadaptation to astronomical work, and itssuccess has had an important effect upon thescience of practical astronomy. No one wouldnow think of locating a great observatorywithout careful consideration of the site to beoccupied. The mountain observatories of theworld owe much to the experiments made atMount Hamilton.

The principal objects of research have been:The visual and photographic observation ofplanets and satellites; the fifth satellite ofJupiter was discovered here by Barnard in 1892.A systematic search for comets has been keptup and 14 unexpected comets have been discovered— Barnard (3), Perrine (9), Coddington(1), besides a comet discovered by Schaeberleuring his observations of the solar eclipse inChile. Many periodic comets have also beendetected and observed. The orbits of newcomets have always been promptly computed atthe observatory and ephemerides sent out toother stations. Four asteroids were discoveredby Coddington in 1898-99. Meteors have beenobserved and photographed, and their orbitscalculated. Double stars have been assiduouslyobserved and many new discoveries made byBurnham, Hussey and Aitken; the orbits of aconsiderable number of binaries have beencalculated. Observations of the zodiacal light andof the aurora have been made by Barnard andothers. Successful expeditions have been sentto observe all total solar eclipses since 1888, andvery much has been added to our knowledge ofsolar physics in this way. The transit of Venusof 1882 and three transits of Mercury have beenobserved and photographed here. Thepositions of a large number of fixed stars havebeen determined with great precision by Tucker.Many photographs of the sun and moon havebeen made. The negatives of the moon havebeen utilized in the preparation of an atlasof the moon (scale 10 feet to the moon's diameter) by Professor Weinek, and on a scaleof three feet by Messrs. Holden and Colton.A great number of important photographs ofthe milky way were made here by ProfessorBarnard and others, and of comets and nebulæby Keeler, Hussey, Perrine and others. Acomplete outfit of seismometers for recording theintensity of earthquake shocks was installed atthe observatory in 1888, and it was supplementedby similar instruments at Berkeley andat other points in California and Nevada, whichregularly report to Mount Hamilton. In thisway the elements for seismometric record forthe State were collected and regularlypublished. At the same time a list of all recordedshocks on the Pacific coast since 1769 wascompiled and discussed by Dr. Holden.Spectroscopic observations of nebulæ, new stars,comets, stars and planets haye been made ingreat number and with previously unattainedprecision by Messrs. Keeler, Campbell, Wright,Perrine and others.

The chief problem of the great telescope isto determine the motion of the solar system byspectroscopic observations. The photography ofstellar spectra was proposed in the plan of 1874and attacked in 1888, and it has been followedwith marked success, especially in the hands ofProfessor Campbell. Since 1896 more than2,000 negatives of stellar spectra have beensecured. A preliminary discussion by Campbellleads to the result that the solar systemis moving toward a point in 277° R. A. and 20°N. D., at a speed of 19.89 kilometers (12.35miles) per second. An expedition was sent(at the expense of D. O. Mills) to the southernhemisphere in 1903 to extend this research tosouthern stars.

The observatory publishes a series of octavo‘Contributions’ (No. 1 in 1889, No. 5 in 1895),of quarto ‘Publications’ (1887 et seq.) and aquarto Bulletin since 1901 — a journal. TheAstronomical Society of the Pacific, foundedby Professor Holden in 1889, has closerelations with the observatory, and has printed15 octavo volumes. Visitors are freelyadmitted to the observatory in the day time tothe number of 5,000 or more annually. OnSaturday evenings visitors are admitted to lookthrough the telescopes, and as many as 150 to200 are frequently registered. In this way theobservatory has rendered important services topopular education.