52 



ASTEONOMICAL PHENOMENA AND PEOGRESS. 



major axis remaining constantly parallel to 

 Jupiter's equator. It seems also, like the solar 

 spots, to have a proper motion upon the sur- 

 face. Mr. Dennett remarks that "between 

 July 27th and November 15th the longitude 

 of its preceding extremity seems to have in- 

 creased some twenty-four degrees, which means 

 a proper motion eastward of more than 230 

 miles per day." In August, 1879, the length 

 of the spot, according to the measures of Pro- 

 fessor Pritchett, was nearly 25,000 miles, and 

 its greatest breadth about 6,400. Other mark- 

 ings, indicative of unusual atmospheric activ- 

 ity, have been noticed during the year, but 

 this " red spot," by its magnitude, color, per- 

 manence, and proper motion, has attracted the 

 special attention of observers. 



The Density of Saturn. In the "Astro- 

 nomische Nachrichten," No. 2269, Professor 

 Asaph Hall of Washington compares the ob- 

 served value of Saturn's polar compression 

 with Laplace's formula for the ellipticity of a 

 rotating homogeneous spheroid. The theoreti- 

 cal value of the ratio of the semi-axes is found 

 to be 1'1859. The observed value is 1-1087 ac- 

 cording to Bessel, or T1223 according to Kai- 

 ser. Consequently, as in the cases of the earth 

 and Jupiter, the polar compression is less than it 

 would be if the mass were homogeneous. The 

 density increases, therefore, from the surface 

 to the center of the planet. Moreover, the 

 rate of variation is more rapid in Saturn than 

 in Jupiter, and, as the mean density of the 

 former is considerably less than the density 

 of water, we may conclude that the surface 

 of Satnrn is in the condition of vapor. 



Meteoric Showers, The meteors of January 

 2d were observed at Bristol, England, by Mr. 

 W. F. Denning. The sky was overcast on the 

 night of the 1st, but toward morning the clouds 

 partly cleared away, and in a watch of twenty 

 minutes, commencing at 6 h ' 14 m- on the morn- 

 ing of the 2d, two thirds of the sky being cov- 

 ered by clouds, fourteen meteors were seen, 

 all belonging to the shower whose radiant is 

 in Quadrans. The shower at this time was 

 evidently very active. Mr. Denning remarks 

 that in a cloudless sky more than one meteor 

 per minute would have been seen by a single 

 observer. The radiant point was at E. A. 230, 

 decl. N. 51. 



The Meteors of August 8th-l%th. The num- 

 ber of August meteors observed in 1879 was 

 rather less than usual. The weather, however, 

 was unfavorable, not only in our own coun- 

 try but also in England. In the " Science Ob- 

 server" for September Mr. Edwin F. Sawyer 

 of Cambridge, Massachusetts, gives the results 

 of his watching on the nights of the 10th, llth, 

 and 12th ; a succession of cloudy nights having 

 prevented any previous observations. On the 

 20th, commencing at 9 o'clock and watching 

 four hours, Mr. Sawyer counted 107 meteors, 

 of which 78 were Perseids. The greatest fre- 

 quency occurred soon after ll h> 30 m -. "Their 

 persistency to grouping was very noticeable, 



and frequently intervals of five minutes and 

 even longer occurred without a single meteor 

 being recorded, and then several being seen 

 almost simultaneously." The radiant was at 

 E. A. 44 30' and decl. N. 57. The number 

 of Perseids observed in 2 hours, beginning 

 at 9 o'clock on the night of the llth, was 27. 

 On the evening of the 12th the shower had 

 nearly ceased. 



The Meteors of November 13th-14th. A few 

 meteors from this interesting stream were seen 

 at several stations. In a watch of two hours, 

 commencing at 3 h - 30 m - on the morning of the 

 13th, Mr. D. E. Hunter of Washington, Indiana, 

 assisted by several students, counted 190 me- 

 teors, the greatest number reported from any 

 one station. 



Relative Numbers of Meteors in Different 

 Months. In order to determine the relative 

 proportion of meteors of all kinds registered 

 by different observers, Mr. W. F. Denning re- 

 cently summarized the results given in twelve 

 catalogues, which comprise 59,086 meteors, and 

 the following numbers were derived: 



January 2,419 meteors. 



February 1,609 " 



March 1,449 " 



April 4,82 1 " 



May 1,133 " 



June 1,825 " 



July ......... 7,8f 9 meteors. 



August 



September. 



October 



November . . 



28,874 

 . 2,897 

 . 4,827 

 5,457 



December 2,903 



Thus August alone contains nearly two fifths 

 of the whole number recorded. 



Origin of the November Meteors. In a lec- 

 ture recently delivered before the Eoyal Insti- 

 tution of Great Britain, Mr. G. Johnstone 

 Stoney, after tracing the history of the No- 

 vember meteors, pointing out their connection 

 with the comet of 1866, and indicating the 

 manner in which they were permanently at- 

 tached to the solar system, presents the follow- 

 ing views in regard to their origin : 



The question now arises, how the deserts of space 

 which extend from star to star come to be tenanted 

 here and there by a patch of gas or an occasional me- 

 teorite ? Light has been thrown on this inquiry by 

 discoveries made with the spectroscope in modern 

 times, and by observations during eclipses. These 

 have revealed to us the fact that violent outbursts oc- 

 cur upon the sun, and doubtless on other stars, so 

 swift that the uprush must sometimes cany matter 

 clear away into outer space. Imagine such a mass, 

 consisting in part of fixed gas and in part of condens- 

 able vapors, ejected from some star. As it travels for- 

 ward the vapors cool into meteorites, while the fixed 

 gas spicads abroad like a great net, to entangle other 

 meteors. In some cases both might travel together ; 

 in others the gaseous portion would be retarded before 

 it passed beyond the neighborhood of the star, and 

 the denser meteors would get ahead. But even so, in 

 the lapse of ages other meteors would be caught, so 

 that in any event a cluster would at length be formed. 

 Now, the reasonable suspicion that this is the real ori- 

 gin of meteors has received striking confirmation from 

 the discovery of the late Professor Graham, that me- 

 teoric iron contains so much hydrogen occluded within 

 it as indicates that the iron had cooled from a high 

 temperature in a dense atmosphere of hydrogen pre- 

 cisely the conditions under which the vapor of iron 

 would cool down while escaping from a large class of 

 stars, including our sun. 



We have now traced an outline of the marvelous 

 history of these Arabs of the sky. We have met with 



