1880.] 



in BeJation to ilie Sun-spot Oijcle. 



73 



duration tban at the Bay islands, and on the average of the whole period 

 not more than half as great ; viz., '020'. 



As far as can be judged, then, from the available evidence, the excess 

 appears to have been greatest (in the Indian region) on an axis lying 

 between the Nicobars and Bengal. And, in Australia, at Adelaide, or possi- 

 bly to the westward of that station. In the absence of any sufRcient 

 registers for Western Australia, this must remain an open question. To 

 the eastward, however, it certainly diminished greatly at Melbourne, and 

 still more at Sydney. Whether, however, the condition of excessive pres- 

 sure was continuous between Batavia and South Australia or otherwise, 

 there is no distinct evidence to show. 



In Asia, the excess was less in Assam than in Bengal, and was compara- 

 tively small at Shanghai (Zi-ka-wei). To the westward, it also diminished, 

 but not quite regularly ; since, in Orissa and on the Gangetic plains, it was 

 less than on the plateaux of Chtitia Nagpur and Bundelkand, and slightly 

 less than in Eajputana and Sind. Some of these irregularities probably 

 depend on variations of the temperature, and therefore density, of the lower 

 atmosphere ; and partly also are apparent only, and owing to the fact that 

 the averages which have served as the standaid of the comjoarison are 

 derived, in some cases, from longer series of years than in others. That, 

 notwithstanding these irregularities, there was, on the whole, a general 

 decrease of the excessive pressure to the westward of the axis above defined, 

 appears, however, pretty clearly, from the following average values of this 

 excess for the whole period of the 28 months of its duration. 



+ ■0132" 

 + -0215" 



+ •0219"Boinbay + -0196" 



+ -0127" W.Coasfc f -0102" 

 + -0199" Ceylon + '020" 



It may here be observed that this axis or ridge of greatest intensity, 

 if prolonged, lay across the middle of the two great continental masses, 

 Asia and Australia, from Western Siberia to South Australia ; a position 

 which suggests the probability that the phenomenon was in some measure 

 dependent on the presence and position of these large land masses. 



The variation of the anomalous pressure from month to month, at all 

 the stations above referred to, is given in the accompanying Table I, which 

 shows the deviation of the pressure, in each month, from tlic average of that 

 month and ]ilaco (or district), as derived froni the registers of many years. 

 10 



Bengal 

 Arakan 

 Bay islands 



•029S" 



f Gangetic 

 plain 

 Chatia 

 Nagpur 



0317"<; &Biindel- 

 0327" kand 



Orissa 



+ •0191", ..Punjab 



I Eajputana ' 



•0284' 



+ 0164" 



I and Sind / 

 Nagpur and 



Berar 

 Dakhan 

 Carnatic 



