276 VARIATION OF LATITUDE. 



Observatious were also made at Pulkova, Eiissia, Greenwicli, and 

 Wasbiugtou. Tbe Wasbingtoii observatious were made between 18G2 

 and 1867, and included six complete periods of 305 days eacb. A rig- 

 orous discussion by Newcomb gave tbe separation of tbe axes as 3 feet, 

 or 0.03". 



C. A. F. Peters, of Pulkova, bad in 1842, obtained 0.079"= 8 feet. 



Tbese figures are small, but fiiirly accordant. A reinvestigation, 

 bowever, sbowed tbat tbe various calculatious did not agree in sbowing 

 tbe same displacement at tbe same time. Tbis made tbe wbole result 

 doubtful, so tbat Newcomb (in 1892, Marcb, Mou. Not. R. A. S.) remarked 

 tbat "tbe observations sbowed beyond doubt tbere could be no inequal- 

 ity of tbe kind looked for." 



It was wbile investigations of tbis kind, to determine tbe separation 

 of tbe axis of rotation and axis of figure, were going on tbat Sir AVil- 

 liam Tbomson (now Lord Kelvin) announced, at tbe congress of tbe 

 Britisb Association at Glasgow iu 1874, tbat tbe meteorological i)be- 

 nomena, tbe fall of rain and snow, tbe cbanges wbicb occur in tbe cir- 

 culation of tbe air and of tbe sea waters, would modify a little tbe 

 mecbanical constitution of tbe globe, and displace a little tbe axis of 

 figure, i. e., tbe form of tbe eartb would be cbanged by tbe causes men- 

 tioned, and so a new sbortest axis would be made. Tbe effect of tbis 

 would be to produce a cbauge in tbe latitudes of places, evidently. He 

 tbougbt tbat it migbt amount to 0.50", wbicb would correspond to a 

 movement of tbe old axis (at tbe pole) of 50 feet on tbe eartb's surface. 

 Sir William Tbomson did not i^ublisb bis calculation, but tbe autbority 

 of tbe great Englisb matbematician and pbysicist was sucb as to make 

 scientific men give tbe statement great attention. Tbese meteorologic 

 pbenomenaof wbicb Sir William Tbomson spoke are annual in cbarac- 

 ter. Wben tbis annual period is combined witb tbe 305-day or ten- 

 montb period of Euler we see tbat complexity results. Tbis was tbe 

 state of tbe investigation wben Dr. Kiistner, of tbe Berlin Observatory, 

 publisbed tbe results of bis observations made in 1884-85. Dr. Kiist- 

 ner undertook some observations for tbe trial of a new metbod for tbe 

 determination of tbe constant of aberration. On reducing bis obser- 

 vations be obtained results wbicb were not at all satisfactory. A care- 

 ful examination of bis work led bim to make tbe announcement tbat 

 tbe unsatisfactory value for tbe aberration constant was due to a com- 

 paratively rapid, tbougb very small, cbange in tbe latitude of tbe Berlin 

 Observatory — " tbat from August to November, 1884, tbe latitude of 

 Berlin bad been from 0.2" to 0.3" greater tban from Marcb to May in 

 1884 and 1885." 



Tbis would indicate tbat from August to November, 1884, tbe i»ole of 

 tbe eartb bad approacbed Berlin more closely by 20 to 30 feet tban in 

 tbe time from Marcb to May. 



Tbis conclusion was fortified by tbe examination of otber data, 

 obtained from tbe observatious made at Pulkova by Nyren. 



