GUDDE: A CENTURY OF ASTRONOMY AND GEODESY IN CALIFORNIA 67 



As the third station, Davidson selected San Diego, because its latitude on 

 the existing charts was completely erroneous. 



At this port [he wrote], I made the usual astronomical observations of lunar transits, 

 occultations of stars by the moon, latitude observations, azimuth observations for the 

 triangulation, determination of the magnetic elements, etc., working the greater part 

 of the night and computing the greater part of the day. I had undertaken work on this 

 coast to make a record in a new field, and therefore labored nearly to the utmost strain 

 of my energies, never less than eighteen hours a day. 



After this first year of astronomic observation and determination the work 

 of the United States Coast Survey was carried on with ever-increasing speed, 

 volume, and variety. Until his retirement in 1895, except for the years during 

 and after the Civil War, which were spent chiefly in war work at Philadelphia, 

 Davidson was in charge of the astronomic, geodetic, topographic, and hydro- 

 graphic work of the Pacific Coast and later also of the coast of Alaska. 



Besides the practical work the members of the Coast Survey inaugurated 

 astronomical observation on the Pacific Coast. While at Monterey Bay in the 

 winter of 1850-1851, Davidson began his computation of the star factor tables, 

 which were later published. In 1852 he discovered and observed a brilliant comet 

 at Astoria on the Columbia Eiver. The solar eclipse of May 26, 1854, was 

 observed by members of the Survey at Benicia, Loma Prieta, and Humboldt Bay. 

 Davidson also observed the solar eclipse of March 25, 1857, in San Francisco. 

 In 1856 he published the "Occultation of Stars by the Moon on Western Coast of 

 the United States," and in the following year "The Occultation of 22 Stars of 

 the Pleiades, and Solar Eclipse of 1857." 



The crowning achievement of Davidson during his first phase of Pacific 

 Coast Survey was a practical work, the Directory of the Pacific Coast, first pub- 

 lished in 1857. This work, republished at irregular intervals and later called 

 Coast Pilot of California, Oregon and Washington, systematized the astronomic, 

 geodetic, hydrographic, and topographic work of the Coast Survey and became 

 the bible of the mariners who sailed up and down the Pacific Coast. 



The year in which Davidson left San Francisco, 1860, witnessed the first 

 attempts of astronomical observations by agencies other than the United States 

 Government. To the University of Santa Clara belongs the honor of being the 

 first educational institution of the State to acquire a telescope. The 4-inch 

 refractor with altazimuth mounting, installed in 1860, was the nucleus of an 

 observatory which in later years became well known, especially through Jerome 

 Eicard's observations of sun spots and faculae. 



In the same year an amateur astronomer, George Madeira, started observing 

 with a 3-incli refracting telescope with equatorial mounting at Volcano, Amador 

 County. According to Campbell, on June 30, 1861, Madeira discovered the 

 brilliant Comet 1861 II only a few hours after its discovery in Europe. 



In the meantime other agencies were at work surveying the State. A United 

 States Commissioner of the General Land Office was sent to California shortly 

 after the treaty of Guadalupe Hidalgo had been signed. The principal tasks 

 of his office were the establishment of the extent of the Spanish and Mexican 

 land grants and the division of the newly acquired territory into townships. 

 The commissioner established the three township base lines and meridians: the 

 Mount Diablo, the San Bernardino, and the Humboldt, which have formed the 



