54 



ASTRONOMICAL PHENOMENA AND PROGRESS. 



With the most probable values of the earth's 

 equatorial radius and the sun's mean horizon- 

 tal parallax, the distances of the satellites 

 from the centre of the primary, expressed in 

 English miles, are : 



Ariel 118,100 



Umbriel 164,550 



Titania - 269,800 



Oberon 860,800 



The masses of the satellites, according to 

 Prof. Newcomb, are probably less than -^^Q^ 

 of that of the planet. Their mutual pertur- 

 bations must therefore be feeble. The distance 

 of Neptune's satellite from the centre of the 

 primary is found to be 218,550 miles, and its 

 period of revolution, 5.8769 days. No other 

 satellite has been seen, though carefully looked 

 for. The doubtful observation by Lassell in 

 1850 was therefore probably an illusion. 



It is a remarkable fact that the orbits of all 

 the satellites of Uranus and Neptune are less 

 eccentric than those of Saturn, Jupiter, and 

 the earth, and that, so far as observations have 

 yet shown, they may be perfect circles. 



The masses of Uranus and Neptune, ob- 

 tained by Prof. Newcomb from satellite obser- 

 vations, are irz ^ and -^^ respectively. 



Color of Uranus. In the monthly notices 

 of the Royal Astronomical Society for March, 

 1875, Captain W. Noble calls the attention of 

 observers to what he regards as a change of 

 color in the planet Uranus. This astronomer 

 for a number of years had always embodied 

 his impressions as to the color of the planet in 

 the words "a pale-blue disk." The first 

 change observed was on the night of March 9, 

 1875, when he was " at once struck with the 

 apparent alteration in the character of its 

 light, which was much whiter and brighter " 

 than he had ever seen it. " Nay, there was 

 even the faintest suspicion of yellow in it, so 

 thoroughly had every vestige of blueness van- 

 ished." As seen through the 26-inch refrac- 

 tor at Washington, the planet, according to 

 Prof. Newcomb, has always presented a sea- 

 green color. 



Binary Stars. The elements of the follow- 

 ing binary systems have been recently deter- 

 mined ; those of the first by Dr. Duner, of the 

 Observatory of Lund, Sweden ; those of the 

 others by Dr. W. Doberck, of Markree Observ- 

 atory, Ireland. We give the periods and eccen- 

 tricities : 



Burnharn's Sixth Catalogue of New Double 

 Stars. We referred, in our last volume, to the 

 important researches in sidereal astronomy by 

 S. W. Burnham, Esq., of Chicago. In the 

 Astronomisches Nachrichten of November 5, 

 1875 (No. 2,062), a sixth catalogue, contain- 

 ing ninety new double stars discovered by 

 a 6-inch refractor, is given by the same dis- 

 tinguished observer. No. 21 of this catalogue 

 is a very interesting system. It is known as 

 3,780 in Herschel's " Cape Observations," 

 where it is described as quintuple, two of the 

 components being of the seventh, and three of 

 the eighth magnitude. Mr. Burnham's exam- 

 ination of these objects, with a view to .sup- 

 ply further details, showed the group to con- 

 sist really of six stars, two of which, on still 

 closer scrutiny, were themselves found to be 

 double, the companions being close and very 

 minute. This remarkable system, consisting 

 of eight members, is just visible to the naked 

 eye as a sixth-magnitude star. It is generally 

 designated as 45 Leporis. 



Gold Medal of the Royal Astronomical Soci- 

 ety. The council of the Royal Astronomical 

 Society of London, in their annual report of 

 February 12, 1875, awarded the gold medal 

 of the society to Prof. Heinrich L. D'Arrest, 

 Director of the Observatory of Copenhagen, 

 for his observations of nebulae, contained in 

 his great work " Siderum Nebulosorum Obser- 

 vationes Havniensis," as well as for other im- 

 portant labors and discoveries. In 1851 Prof. 

 D'Arrest discovered the periodic comet which 

 bears his name, and in 1862 he detected the 

 minor planet Freia, the seventy-sixth of the 

 group between Mars and Jupiter. It has been 

 his chief work, however, to determine, with as 

 much accuracy as possible, the positions of 

 nebulsa discovered by the Herschels, Lord 

 Rosse, and other observers. His labors in this 

 department of research will enable future as- 

 tronomers to determine the proper motions of 

 those interesting objects, if indeed such mo- 

 tions shall be susceptible of measurement. 



AUSTRALIA AND POLYNESIA. The 

 area and population of Australia and Polynesia 

 were, according to the latest accounts, as 

 shown in the table on page 55. 



The principal occupations in Australia are 

 agriculture, stock-raising, and mining. The 

 climate, almost throughout the continent, is 

 favorable to the products of the soil. Wheat, 

 maize, barley, oats, and potatoes, are the arti- 

 cles most largely cultivated, while tobacco 

 and sugar also nourish. The vine has of late 

 years been extensively introduced, for wine- 

 making. 



In New South Wales 454,635 acres of land 

 were under cultivation in 1872, of which wheat, 

 with 177,552 acres, and maize, with 116,745 

 acres, occupied the larger part. From this 

 land 2,898,463 bushels of wheat and 3,984,958 

 bushels of maize were obtained. The total 

 number of acres of land occupied was 9,788,728 

 acres, of which 454,635 acres are under culti- 



