36 



According to the publications of the Pola Observatory,* the excesses in the observed over the theoretical 

 values were as follows : 



g observed - g calculated (by VON HELMERT'S formula). 



Auckland +0-111 



Brisbane +0-067 



Hobart +0-064 



Melbourne +0-062 



Sydney +0-097 



The Austrian observations at Melbourne and Sydney were carried out in 1893 and 1897. Observations 

 were also made at these two stations by Mr. P. BARACCHI and Mr. E. F. J. LOVE in 1893-4, using 

 RATER'S pendulums. Mr. LOVEJ gives only the times of swing, not the absolute values of </, but the 

 differences in the times of swing observed at Sydney and Melbourne accord fairly well with the difference 

 between these two stations deduced by the Austrian observers. Though he does not give absolute values 

 of ff, Mr. LOVE gives the time of swing of the Kater pendulums at Greenwich ; from these one would 

 deduce for Melbourne a lower value of g than that obtained by the Austrian observers, or by 

 Mr. BERNACCHI. 



10. An outstanding feature is the very considerable difference between the results obtained at Winter 

 Quarters in July-August, 1902, and September, 1903, on the one hand, and those obtained in February, 

 1903, on the other. The most natural direction in which to seek an explanation of such a discrepancy is 

 in error either in the observations themselves or in their reduction. The data have been so carefully 

 checked that the possibility of observational error in the readings, or of arithmetic error in the reductions, 

 may, I think, be dismissed. The mean values of the pressure and temperature during the series of 

 observations at Winter Quarters were as follows : 



Pressure Temperature, 



(in millims.). 0. 



July- August, 1902 83-2~) 7g . 6 ~ 1 ' 6 "l-l-l 



September, 1903 74'OJ -0-6/ 



February, 1903 87-1 -1-0 



The differences in the mean pressure and temperature are so small that no conceivable error in the 

 values accepted for the -pressure and temperature coefficients could supply an adequate explanation. The 

 same pillar was used throughout, so difference in the "flexure "is an impossible explanation unless the 

 condition of the pillar in February predisposed to " flexure " immensely more than in July, August, or 

 September. Such a difference would have appeared less improbable if the February mean temperature (in 

 the hut) had been much higher than on the two other occasions, instead of occupying, as it did, an 

 intermediate position. If the cause is observational, its most probable source would seem to be error in 

 the rates deduced for the chronometer. 



Mr. BERNACCHI refers to this point in his introduction, and mentions as a possible explanation the large 

 northward movement of ice occurring in the Antarctic summer prior to February. Exactly how the Earth 

 behaves under the removal of a load, and what compensations may come into play under the conditions 

 existent in the Antarctic, are matters about which we know too little at present to draw conclusions of 

 value. At present, I am afraid, remembering the sources of uncertainty, the only prudent course is to 

 reserve judgment. The point is one, however, to which the attention of future observers may well be 

 directed. 



* ' Veroffentlichungen des Hydrographischen Amtes der k. u. k. Kriegs-Marine in Pola,' Gruppe III. Relative Scliwen 1 - 

 bestimmungcu. Heft III., Pola, 1902. 



t ' Roy. Soc. Victoria Proc.,' March, 1894. 



