Dec. 7, 1888.] 



SCIENTIFIC NEWS. 



577 



RECENT ASTRONOMICAL WORK AT 

 THE LICK OBSERVATORY. 



THE Lick Observatory was transferred to the Regents 

 of the University of California on June 1st, 1888, 

 and has, therefore, been in active operation as a State 

 institution for about four months, and much of this 

 time has been devoted by the astronomers to studying 

 the instruments under their charge, and determining 

 the constants necessary for future work, the great tele- 

 scope naturally claiming the largest share of attention ; 

 but many observations of important phenomena have 

 been made, and the objects of greatest interest in the 

 sky have been carefully examined with a view to the 

 discovery of new features, as well as for the purpose of 

 testing the performance of the lens. The sun has not 

 yet been observed with the great telescope, but it is 

 doubtful whether any advantage can be gained here in 

 the study of his surface by the use of a large instru- 

 ment. The seeing on Mt. Hamilton is usually poor in 

 the daytime, owing probably to the heated air of the 

 surrounding valleys, which is rapidly cooled at night by 

 radiation or shut in by the fogs which then pour in from 

 the ocean. 



Mercury and Venus have been seen in the daytime 

 only, and, therefore, under the same disadvantageous 

 circumstances. There are, however, days of good see- 

 ing, when the features of these planets can be profitably 

 studied. The moon is a most beautiful and interesting 

 object with the great telescope. It was photographed 

 throughout an entire lunation in August, and the pic- 

 tures then obtained are a distinct advance-on all previous 

 work in this direction. The diameter of the lunar 

 image on the negatives is five and a quarter inches, and 

 with the plates used the exposure required was a little 

 less than half a second. Observations were made 

 with the various instruments during the total lunar 

 eclipse of July 22nd, and will be published in the 

 memoirs of the National Academy of Sciences. Mars 

 had become too low in the west after the transfer of the 

 Observatory to be well seen. Numerous drawings were, 

 nevertheless, made by Professor Holden, Mr. Schaeberle, 

 and Mr. Keller, and published in the Astronomical Journal. 

 The principal canals of Schiaparelli were seen, not as 

 double, but as single, ill-defined lines ; and the conti- 

 nent of Libya, which, according to M. Perrotin, had 

 been submerged or did not exist during April and May, 

 appears on the drawings in its usual shape and position. 

 The micrometer observations of the satellites made by 

 myself when the planet was in opposition have been 

 published in the Astronomical Journal. The satellites, 

 which appear to have been seen with great difficulty 

 elsewhere, were bright and easy objects with the 36- 

 inch equatorial — a fact which affords gratifying testimony 

 as to the instrument, and the excellence of the atmo- 

 spheric conditions. Phobos was seen on July 1 8th, when 

 its brightness was only o - 2 2 of that at mean opposition, 

 and one-eighth of that at the time of discovery by 

 Professor Hall. From the ease with which this satellite 

 was seen in close proximity to the planet, it seems to me 

 probable that we can observe eclipses during favourable 

 oppositions, and determine the mean motions of the 

 satellites with greater accuracy than is obtainable by 

 micrometer observations. 



Jupiter was frequently examined on fine nights in June 

 and July. His surface showed a wealth of delicate 

 detail which would have required a much longer time to 



record satisfactorily than it was possible to give. A 

 number of observations were made of curious appear- 

 ances presented by the shadows of satellites in transit. 

 The satellites themselves appear as large and well- 

 defined discs. Saturn has not been observed since the 

 telescope was first mounted in January. It was then a 

 splendid object, all the wonderful details of the system 

 shining with a brilliancy and distinctness probably never 

 before equalled. The outlines of the rings were sharp 

 and clear, and a fine, dark line was seen close to the 

 outer edge of the outer ring, with a dark shading extend- 

 ing inward toward the great black division. The gauze 

 ring was very conspicuous. Neptune has been observed 

 by Professor Holden and Mr. Schaeberle, and (with its 

 satellite) has been photographed several times. Many 

 double stars have been discovered and measured by Mr. 

 Burnham with the 36-inch and 12-inch equatorials. 

 Perhaps the most interesting of this class of objects 

 discovered with the aid of the large telescope is the 

 star pv (Gamma) 7 Cassiopese, which is found to have a 

 minute companion distant 22", in position angle 256 . 

 It has been frequently observed lately with the 12- 

 inch equatorial. Difficult stars, previously known, have 

 also been measured by Mr. Burnham. The planetary 

 nebulas have been studied by Professor Holden and Mr. 

 Schaeberle, who have observed in several of these objects 

 curious helical forms, which do not appear in earlier 



Electric Control of the Clock of the Great 

 Telescope. 



drawings with smaller instruments. The ring nebula in 

 Lyra is a wonderful object in the great telescope. The 

 central star, discovered by Von Hahn, is very con- 

 spicuous, and four other stars of exceeding minuteness 

 appear within the limits of the inner ellipse, while a star, 

 almost as bright as the one in the centre, is seen exactly 

 at the proceeding extremity of the major axis of the 

 ring. Many other small stars not so critically situated, 

 and therefore less interesting, are seen in proximity to 

 the nebula. These minute stars are beyond the range 

 of all but the most powerful telescopes, although it may 

 be noted that there is a class of observers with very 

 small telescopes prepared to immediately "verify" all 

 discoveries made by powerful instruments, even when, 

 as has sometimes been the case, the supposed discoveries 

 are afterward found to be purely fictitious. There 

 is no way of disproving that a difficult object can 

 be seen by such an observer with an apparently 

 inadequate instrument, or of showing that excess of 

 zeal is made to take the place of sufficient optical 

 power. Mere size, it is true, unaccompanied by other 

 qualities, counts for but little, and the greater part 

 of astronomical work has been done by skilled observers 



