756 Traxsactioxs of the American Institute. 



The ArrROAcn of Sirius. 



Mr. Ilnggins lias made a subtle application of spectroscopic 

 analysis, by which lie determines whether a celestial body is approach- 

 ing or receding in consequence of a change in the refrangil)ilitics of 

 light produced by a modification of the ethereal waves. lie announces 

 as one of the remarkable results of his investigations that the bright 

 fixed star Sirius is approaching the solar system at the rate of twenty- 

 nine and a half miles per second. 



PERTrRBATIONS OF OUR PlANET. 



That class of perturbations known as " secular," have been pro- 

 foundly investigated by John L. Stockwell, who, in the July number 

 of The American Journal of Science and Arts, under the title of 

 " The Secular Variations of the Elements of the Earth's Orbit," has 

 given the results of his computations showing the eccentricity of the 

 earth's orbit during a million of years ; and this is but a continuation 

 of calculations, previously published by him, extending over the 

 preceding million of years ; so that his tables and charts now include 

 more than '2,000,000 of years. The materials used in the preparation 

 of the formulas on which the tables are based are the same as those 

 used i'U the construction of the Arnerican Ephemeris and Nautical 

 Ahnanctc with the exception of the mass of the earth which has been 

 increased 1-351132. Mr. Stockwell has determined anew tke secular 

 variations of the elements of the orbits of the eight principal planets, 

 and the constants obtained differ somewhat from those obtained by 

 Le Verrier, who made his investigation before the discovery of 

 neptune and the correction of values relating to the masses and 

 elements of other planets. From Le Yerrier's formula croll, some 

 years ago, made and published a similar computation to that of 

 StockwelFs, but it was much smaller, and was based on much longer 

 intervals, namely, 50,000 years. By using intervals of 10,000 yeai's, 

 Stockwell is enabled to show many maxima and minima, which it is 

 evident would escape notice if the chart was curved by eveiy fifth 

 ordinate. The new chart indicates a curious relation, not so easily 

 discovered by exainining the figures of the table^, and that is, that 

 the points of maxima and minima are approximately repeated at 

 intervals of 1,4-50,000 years. In conclusion, the author expresses 

 a hope, which we are happy to change to a positive assertion ; 

 we are confident his results will be found of great service in tlie 

 discussion of those problems of terrestrial physics in which solar 



