152 



SCIENCE. 



MOUNTAIN SITES FOR ASTRONOMICAL OB- 

 SERVATIONS.* 

 By Professor O. Stone. 



The question of employing mountain sites for Astron- 

 omical Observations is one of considerable importance, 

 and two papers, recently published, add materially to the 

 meagre literature on this subject. The first of these is a 

 report of a series of observations on Mt. yEtna made by 

 Professor Langley during a visit to Europe in the winter 

 of 1878. 



The lower portion of Mt. ^Etna is described as densely 

 inhabited and covered with rich vegetation. At an ele- 

 vation of about 2000 feet, however, this suddenly ceases, 

 and above this, with the exception of a few uninhabited 

 plantations of chestnut trees which extend to an altitude 

 of 4000 or 5000 feet, there exist only wastes of lava. 

 At an elevation of some 4200 feet a station was estab- 

 lished in a hut built of lava, known as "Casa del 

 Bosco." 



Professor Langley remained upon the mountain from 

 Christmas until January 14. His instruments consisted 

 of a 2> l 4 inch telescope loaned by the superintendent of 

 the U. S. Naval Observatory and a spectroscope provided 

 with a Rutherford speculum metal grating of 17,296 lines 

 to the inch, and with collimating and observing telescopes 

 of I.I inch aperture and 14 inches focal length. 



On clear nights, at ordinary elevations, Professor 

 Langley does not recognize steadily more than six stars 

 in the Pleiades, and on an ordinary clear night at Alle- 

 gheny he cannot steadily see the companion of Polaris 

 with less than two inches aperture. On Mt. M\na, how- 

 ever, he could see steadily, notwithstanding the moon- 

 light, nine stars of the Pleiades, with the naked eye, the 

 companion of Polaris, with an aperture of 1.6 inch and 

 um. companions of [i Leporis and a Tauri, and 1 and a 

 Orionis with 3X inch. From this he concludes that 

 stars of about two thirds the brightness of those visible 

 in England under like telescopic power can be seen on 

 jEtna at the elevation of Casa del Bosco. As far as 

 transparency was concerned, a noticable advantage over 

 stations at a lower altitude was also shown by observa- 

 tions ot the sun. 



The results in regard to steadiness of definition were 

 not so satisfactory. Although there was probably less 

 tremor in the stars as seen from Mt. ^Etna than would 

 have been the case at a lower station, the difference was 

 not great. 



The other paper referred to is the report of Mr. Burn- 

 ham to the Trustees of the "James Lick Trust " of Ob- 

 servations made on Mt. Hamilton with reference to the 

 location of the Lick Observatory. 



Mt. Hamilton seems to have been first suggested as a 

 site for the observatory by Professor Holden in 1874, and 

 afterwards approved by Professor Newcomb. The ele- 

 vation of the summit is 4250 feet, or only a little greater 

 than that of Professor Langley's station at Casa del Bos- 

 co. On this summit Mr. Burnham erected a temporary 

 observatory in which was mounted the magnificent six 

 inch Clark refractor, with which nearly all his double star 

 discoveries had been made. It was equatorially mounted 

 with circles and driving clock. The eye-pieces gave 

 powers up to 400. In addition, a set of meteorological 

 instruments were employed. 



Mr. Burnham remained upon Mt. Hamilton just 60 

 days, from August 17 to October 16, with the exception 

 of three days, September 21-23, spent in San Francisco. 

 As the seeing was first class for the 14 nights imme- 

 diately preceeding the 3 days he was absent, it is fair to 

 presume the same conditions continued. During the 



♦Obkcrvations on Mount Etna, liy S. P, Langley. From the A mcr ican 

 •Journal n/ Sciinct, Vol. XIX, July, 1880. 



Report to the Trustees of the "James Lick Trust," of Observations 

 on Mt. Hamilton with reference to the location of Lick Observatory ; 

 by S. W. Bumham, Chicago, 1880. 



whole time only 1 1 nights were cloudy or foggy, and of 

 the iemaining nights there were 42 when the seeing was 

 first class and 7 when it] was medium, and no poor 

 nights when the sky was clear. Besides obtaining re- 

 markable results in the examination of delicate test ob- 

 jects, a search was made for new doubles, and at the 

 close of the report Mr. Burnham gives a catelogue with 

 observations of 42 such objects, 10 of which have a dis- 

 tance of less than 1". A great many objects were ex- 

 amined by daylight but the air, during the greater part 

 of the day at least, appeared to be no steadier than would 

 be ordinarily found elsewhere. 



In conclusion, Mr. Burnham says : " So far as one may 

 judge from the time during which these observations 

 were made, there can be no doubt that Mt. Hamilton 

 offers advantages superior to those found at any point 

 where a permenent observatory has been established. 

 ****** The ease vvith which close pairs can 

 be seen, almost down to the horizon, will be apparent 

 from the southern declination of many of the new double 

 stars. * * * * Close pairs can be observed at least 

 down to 42° south declination. * * * * * 



"What has been said about the advantages of Mt. 

 Hamilton for astronomical purposes, is of course, based 

 upon what was seen during the time spent on the moun- 

 tain. This was my first visit to the Pacific coast, and 

 hence I have no personal knowledge concerning other 

 seasons of the year. From inquiries in various quarters 

 I am satisfied there was nothing about this season un- 

 usual, and there seems to be every reason for supposing, 

 as the same cloudless sky and dry air prevails from 

 about March until the commencement of the rainy sea- 

 son, near the close of the year, that the whole of this in- 

 terval would be equally favorable for the use of the 

 telescope.' 



One of the most remarkable and interesting conditions 

 observed was the dryness of the atmosphere. The aver- 

 age difference between the wet and dry bulb thermome- 

 ters was i8".4 during the first five weeks of Mr. Burn- 

 ham's residence on Mt. Hamilton and every night was 

 first class when this difference reached 15 and upwards. 



Notwithstanding, however, the advantages of a moun- 

 tain site for an observatory, there are many drawbacks. 

 Even the loneliness of the situation is a disadvantage to 

 the greatest activity. Taking everything into considera- 

 tion, therefore, probably as favorable a location as any 

 for the next great American observatory is to be found 

 on the plateaus of Colorado. 



We have received the following publications from the 

 U. S. Department of the Interior (Bureau of Education). 



The Indian School at Carlisle Barracks which 

 acquaints educators and school officials with the interesting 

 experiments of training Indian children in the knowledge 

 and usages of civilized life, in progress during the past 

 eight months at Carlisle Barracks. 



Vacation Colonies for Sicklv School Children 

 This subject has for some time n ceived the attention of 

 this department, and as early as 1872 papers by that dis- 

 tinguished and benevolent physician, J. M. Toner, M. D., 

 of Washington, were published, advocating free camping 

 grounds or parks, where poor children and their parents 

 could lodge during the excessive heat of summer. 



Progress of Western Education in China and Siam. 

 This is an interesting account of the progress of Western 

 ideas and educational methods in China and Siam, for- 

 warded to the department by the United States Minister at 

 Peking, and the United States Consul at Bangkok. 



Legal Rights of Children. This is an elaborate report 

 covering nearly a hundred pages, and treats of the rights of 

 children in the various States of the Union, including edu- 

 cation, and also a comparative view of the systems of edu- 

 cation in the different States established to give force and 

 effect to those rights, and thus assure the welfare of the 

 individual and the State. 



