Dboembkb 14, 1900.] 



SCIENCE. 



917 



ducing the increased radiation. The area 

 of these being much larger a considerable 

 difference of radiation might be expected 

 — a fact it was all the more necessary to 

 point out, because the insignificance of the 

 area occupied by the spots had been used 

 as an argument against any easily recog- 

 nized connection between solar and terres- 

 trial meteorological changes. Assuming 

 two belts of prominences north and south 

 10° wide, with their centers over latitude 

 16°, one-sixth of the sun's visible hemi- 

 sphere would be in a state of disturbance. 

 The authors' object in studying rainfall 

 was to ascertain whether the phis and minus 

 temperature pulses in the sun were echoed 

 by plus and minus pulses of rainfall on the 

 earth. The rainfall tables published by 

 the Indian Government were first studied 

 with special reference to the southwest 

 monsoon, and it soon became evident that 

 in many parts of India the "plus and minus 

 conditions of solar temperature were ac- 

 companied by plus and minus pulses produc- 

 ing pressure changes and heavy rains in the 

 Indian Ocean and surrounding land. These 

 occurred generally in the first year follow- 

 ing the mean condition — viz., in 1877-78 

 and 1882-83, dates approximating to, but 

 followed by, the maximum and minimum 

 periods of sunspots. It was especially in re- 

 gions such as Malabar and Konkan, where 

 the monsoon struck the west coast of India, 

 that the sharpness and individuality of 

 these pulses were the most obvious. The 

 study of Eliot's table of the rainfall of all 

 India from 1875 to 1896 revealed predomi- 

 nant pulses in 1889 and 1893, following 

 those of 1877-78 and 1882-83, so that it 

 enabled the working of the same law —of 

 the mean solar temperature being followed 

 by a pulse of rainfall — to be (raced through 

 another sunspot cycle. The ' whole India ' 

 curve between 1875 and 1896 was also used 

 to test whether the sun pulses, which were 

 found to be bound up with the Indian rain- 



fall, were in any way related to the varia- 

 tions often pointed out in the snowfall on 

 the Himalayas ; it was found that the 

 values occurring at the plus and minus 

 pulses were among the highest. Hence it 

 appeared that the quantity both of rain and 

 snow was increased in the years of the rise 

 both of the unknown and of the iron lines. 

 For the Mauritius the rainfall curve, plotted 

 from 1877 to 1886, was seen to be fairly 

 regular, showing alternately an excess and 

 a deficiency of rainfall. The highest points 

 of the curve were reached in 1877 and 1882, 

 the lowest in 1880 and 1886. Thus the 

 maximum rainfall of 1877 occupied about a 

 year after the rise of the known lines in 

 1876, while the next pulse of rainfall in 

 1882 followed the succeeding crossing when 

 the unknown lines were going up, also about 

 a year later. The curves expressing the 

 rainfall for the Cape and Cordoba for the 

 same period showed two prominent maxima 

 in the years 1878 and 1883, corresponding 

 nearly with the plus and minus pulses of so- 

 lar temperature. On comparing them also 

 with the Bombay and Mauritius curves for 

 the same period, it was found that the 

 pulses indicated at Bombay occurred simul- 

 taneously with those of 1878 and 1883, but 

 in Mauritius the effect of each of the pulses 

 was felt a year or so earlier — namely in 

 1877 and 1882. The rainfall curve for Ba- 

 tavia for this period had its prominent 

 maximum in 1882, as in Mauritius, thus pre- 

 ceding by a year the pulse felt at the Cape, 

 Cordoba and Bombay in 1883. 



Unless the pulses either overlapped or 

 became continuous, there would obviously 

 be intervals between the ending of one and 

 the beginning of another. The plus and 

 minus pulses, to which attention had chiefly 

 been directed, were limited in duration, 

 and when they ceased the quantity of water 

 falling in the Indian area was not suiBcient 

 without water storage for the purposes of 

 agriculture. They were followed, therefore, 



