May 24, 1895.] 



SCIENCE. 



5G5 



the first attempt, and was unsuccessful, it 

 was supposed until recently.* 



Observations were also made at Pulkova, 

 Russia, Greenwich and Washington. The 

 Washington observations were made be- 

 tween 1862 and '(57, and included six complete 

 periods of 305 days each. A rigorous dis- 

 cussion by Kewcomb gave the separation 

 of the axes as .3 feet, or 0.03". 



C. A. F. Peters, of Pulkova, had in 18-12, 

 obtained ".079 = 8 feet. 



These figures are small, but fairly accord- 

 ant. A reinvestigation, however, showed 

 that the various calculations did not agree 

 in showing the same displacement at the 

 same time. This made the W'hole result 

 doubtful, so that Newcomb (in 1892, March, 

 Mon. Not. E. A. S.) remarked that "the 

 observations showed beyond doubt there 

 could be no inequalitj- of the kind looked 

 for." 



It was while investigations of this kind, 



* Tiskserand says in Ann. Bur. Lonfr. '9.5 ( P. 42, 

 B. 11 ) that there is a letter of April 7, 1846, in which 

 Humboldt replies to Gaus.s that Bessel had told him 

 in 1844 that his observations showed that his latitude 

 had decrea-sed 0. 3" in two j'ears. Bes.sel attributed 

 this variation to changes accomplished in the interior 

 of the globe. See also Hasan's letter in Astr. Xach., 

 September, 1894. 



In tliis connection it ought to be noted also that 

 Prof. J. C. Maxwell read a paper April 20, 1857, 

 before the Royal Society of Edinburgh (see Transac- 

 tions Roy. Soc. Edinburgh, Vol. XXI., Part iv., pp. 

 559-571), 'On a Dynamical Top for exhibiting the 

 phenoinena of the motion of a system of invariable 

 fonn about a (ixed point, with some suggestions as 

 to the earth's motion.' He deducetl a period of 325.6 

 solar days. He examined the observations of Polaris 

 made with the Greenwich Transit Circle in the yeiirs 

 1851-54. He found the apjiarent co-latitude of Green- 

 wich for each month of the four years specified. 



" Tliere appeared a very slight indication of a 

 maximum belonging to the set of months, March, '51 ; 

 February, '52; December, '52; November, '53; Sep- 

 tember, '54." Tliis result, he says, "is to be re- 

 garded as very doubtful, as there did not appear to 

 he evidence for any variation exceeding half a second 

 of space and more ol>servation8 would be requiretl to 

 establish the existence of so small a variation at all." 



to determine the separation of the axis of 

 rotatiou and axis of figure, were going on 

 that Sir Wm. Thomson (now Lord Kelvin) 

 announced, at the Congress of the British 

 Association at Glasgow in 1874, that the 

 meteorological phenomena, the fall of rain 

 and snow, the changes which occur in the 

 circulation of the air and of the sea waters 

 would modify a little the mechanical con- 

 stitution of the globe, and displace a little 

 the a.ris of figure, i. e., the form of the 

 earth would be changed by the causes men- 

 tioned, and so a new shortest axis would 

 be made. The efiect of this would be to 

 produce a change in the latitudes of places, 

 evidently. He thought that it might 

 amount to ".50, which would correspond 

 to a movement of the old axis (at the pole) 

 of 50 feet on the earth's surface. Sir W. 

 Thomson did not publish his calculation, 

 but the authority of the great English 

 mathematician and physicist was such as to 

 make scientific men give the statement 

 great attention. These meteorologic phe- 

 nomena of which Sir William Thomson 

 spoke are annual in character. When this 

 annual period is combined with the 305- 

 day or ten-month period of Euler we see 

 that complexity results. This was the 

 state of the investigation when Dr. Kiist- 

 ner, of the Berlin Observatory, published the 

 results of his observations made in 1884- 

 1885. Dr. Kiistncr undertook some obser- 

 vations for the trial of a new method for 

 the determination of the constant of aber- 

 ration. On ri'duciug his observations he 

 obtained results which were not at all sat- 

 isfactory. A careful examination of his 

 work led him to make the announcement 

 that the unsatisfactory value for the aberra- 

 tion constant was due to a comparatively 

 rapid, though very small, change jn the lat- 

 itude of the Berlin Observatory — "that from 

 August to November, 1884, the latitude of 

 Berlin had been from ".2 to ".3 (//ca^tT than 

 from March to ]May in 1884 and 1885." 



