50 



ASTRONOMICAL PHENOMENA AND PROGRESS. 



years before the epoch of the integral in the 

 treatise mentioned. Erom Mr. Stockwell's cal- 

 culations, it appears that, if at any epoch there 

 is a maximum or minimum of any given mag- 

 nitude, in 1,450,000 years before or after that 

 epoch, there will be a corresponding maximum 

 or minimum. A computation similar to this, 

 prepared by Mr. James Croll, and published in 

 the Philosophical Magazine, for February, 

 1867, was based upon Le Verrier's formulas : 



Table showing the Elements of the Earth's Orbit during 

 " of one million of years. 



Distance of the Sun. The problem of the 

 sun's distance has lately been reinvestigated 

 by Mr. Stone, first assistant of the Royal Ob- 

 servatory, Greenwich. He has found that 

 previous calculators, including Encke, have 

 fallen into some mistakes in their use of the 

 recorded observations of the transit of Yenus. 

 In consequence of the effects of irradiation of 

 the sun's light as the planet passes on and off 

 his disk, the phenomenon is somewhat compli- 

 cated, and discoverers made use of different 

 terms in describing it. Some of these expres- 

 sions, according to Mr. Stone, have been mis- 



interpreted by calculators. He has found that 

 when those observations are compared to- 

 gether, which are really comparable, the re- 

 sult is that the sun's horizontal parallax is 

 8".91, very closely agreeing with that derived 

 from the observations of Mars, in 1862. The 

 mean distance of the sun, deducible from this 

 parallax, is 91,740,000 miles. That which is 

 deducible from the opposition of Mars (sun's 

 parallax 8".94) is 91,430,000. The transit of 

 Venus in 1882 will afford a most favorable op- 

 portunity to estimate the distance of the sun ; 

 better than the transit which will occur in 

 1874. 



Asteroids. Reported discoveries of new mi- 

 nor planets during the year brought up the 

 whole number now known to 106. M. Ooggia, 

 at Longchamp, Marseilles, discovered No. 96 

 February 17th. On the same night, M. Tempel, 

 of Marseilles, added another to the list, No. 97, 

 and named it Clotho. M. Tempel requested 

 the finders of the next two planets to accept for 

 them the names Lachesis and Atropos, in order 

 that the three sister Parcas might together 

 complete the first hundred of the planets. 

 When Le Yerrier announced to the French 

 Academy of Sciences the discovery of planet 

 96, M. Delauny took exception to the repre- 

 hensible practice of withholding the names of 

 the subordinates in government observatories 

 by whom discoveries of comets and planets may 

 be made. He added that the discoverer of 

 planet 91 (./Egina) was M. Borelly. Profes- 

 sor Watson has named two planets discovered 

 by him in 1867 as follows: 93, Minerva, and 

 94, Aurora. To the United States belongs the 

 honor of finding the majority of the new plan- 

 ets of 1868. On the 18th of April, Professor 

 0. H. F. Peters, of Clinton, N. Y M discovered 

 98. Its situation was reported as follows : 



Ham. Coll. M. T. 

 April 18, ll h 45 13" 



3Q3.89 ! 



12".7 



Planet 99 was discovered by M. Borelli, at Mar- 

 seilles, on the 28th of May. His observation 

 was: 



Marseilles M. T. a. 8 



May 28, 10 26 m 51" 13* 24 7 8 .92 . 9 5> 49".l 



The planet was then of the 13th magnitude. 



Professor James 0. Watson, of Ann Arbor, 

 Mich., discovered No. 100 July llth, and named 

 it Hecate. It shone like a star of the 10th mag- 

 nitude. On the 15th of August he discovered 

 101, and gave it the name of Helena. Ele- 

 ments of the two planets furnished by Profes- 

 sor Watson to the American Journal of Science 

 are as follows: 



Epoch 

 M 



log a = 



Hecate (100). 



1868, Sept. 1.0 Washington M. T. 



10 5' SO" A 

 304 45 .5) 

 128 28 37 .7 Y Ecliptic and mean equinox 1868.0. 



6 33 34 .6) 



8 39 32 .5 



0.493331 



2.810010 

 = 645".669 



