The great telescope mounted in 1888, a 36-inch refractor by Alvan Clark, has fulfilled every expectation of its projectors, and justified the selection of the site in every particular. The elevation, although moderate, is still high enough to secure very marked advantage in clearness and steadiness of the air, and at the same time not so high that the health and activities of the observers are appreciably affected by the thinner air of the summit. This telescope is known the world over for the monumental contributions to science made by the able astronomers who have worked with it: among them Barnard who discovered the fifth satellite of Jupiter in 1892; Burnham, Hussey, and Aitken, who have discovered and measured thousands of close double stars; Keeler, who spent many faithful years on the summit; and Campbell, the present director, whose spectroscopic researches on stellar movements have added greatly to our knowledge of the structure of the universe. Among the many lines of research now in progress at the Lick Observatory and in the D. O. Mills Observatory at Santiago, Chile, are the discoveries of stars whose velocities in space are not constant, but variable with the spectral type of the star. Mr. Lick's bequest for the Observatory was about $700,000. So ably has this scientific trust been administered that he might well have endowed it with his entire estate, exceeding $4,000,000. Another California mountain that was early investigated is Mount Whitney. Its summit elevation is nearly 15,000 feet, and in 1881 Langley made its ascent for the purpose of measuring the solar constant. He found conditions much more favorable than on Mount Etna, Sicily--elevation about 10,000 feet--which he had visited the year before. But the height of Mount Whitney was such as to occasion him much inconvenience from mountain sickness, an ailment which is most distressing and due partly to lack of oxygen and partly to mere diminution of mechanical pressure. Mount Whitney was also visited many years after by Campbell for investigating the spectrum of Mars in comparison with that of the moon. Langley found on Mount Whitney an excellent station lower down, at about 12,000 feet elevation; and by equipping the two stations with like apparatus for measuring the solar heat, he obtained very important data on the selective absorption of the atmosphere.