188].] 



and rainfall to temperature in India. 



73 



was brought out in the data discussed in the paper. As regards India, I 

 go beyond Mr. Archibald, however, in attributing even greater importance 

 to the evaporation of rainfall than to obscuration of the sun by cloud. 



In a short paper, written in reply to some criticisms of Dr. Hann and 

 Dr. Koppen, which I have lately communicated to the Journal of the Aus- 

 trian Meteorological Society, I had given some recent data which bear 

 strongly on these views ; since they show that both the ground tempera- 

 ture and that of the lowest stratum of the atmosphere are dependent, in a 

 very high degree, on cloud and rainfall ; and that, in India at least, this 

 effect is so great, that it must, in all probability, outweigh and mask any 

 direct influence of variations in the intensity of the solar radiation. 



In the first place, I give a comparison of the mean temperatures of 

 the air and ground at Alipore (Calcutta) Observatory, in the first five 

 months of the two years 1879 and 1880. The air temperatures are those 

 recorded under a shed of the usual pattern, consisting of a thatched roof 

 simply supported on posts, and open, therefore, on all sides to the wind, 

 beneath which the instruments are exposed, about 4 feet above the ground. 

 The ground temperatures are obtained with a verified standard thermome- 

 ter, the bulb of which rests on the ground at the bottom of a wooden tube, 

 3 feet below the surface, the arrangement being similar to that known as 

 Lamont's. The place of exposure is a grassy surface, (the grass being 

 short and in the dry weather thin), freely exposed to sunshine and rain : — 





Temperature. 



Cloud 



PRO- 



Rainfall : 



Rainy 







Air. 



Ground. 



PORTION. 



INCHES. 







1879. 



1880. 



1879. 



1880. 



1879. 



1880. 



1879. 



1880. 



1879. 



1880. 



January, . . 

 February, ... 



March, 



April, 



May, 



Mean or Sum 

 Difference,... 



65-0 

 71-7 

 79-1 

 85-2 



85-2 



77 2 



65 8 

 699 

 786 

 84 2 

 83-6 



76-4 

 —0-8 



72-4 

 74-5 

 798 

 86-3 

 90-2 



80-6 



726 



74-7 

 78-3 

 84 1 

 85-5 



79-0 

 —1-6 



0-39 

 174 

 0-79 

 2 43 

 4-59 



1-99 



2-03 

 305 

 2-72 

 2-64 

 5-21 



3-13 

 + 1-14 



Nil 

 021 



Nil 

 Nil 

 322 



3-43 



005 

 2-91 

 0-54 

 1-91 



4-87 



10-28 



+ 6-85 



"i 



"9 

 10 



1 



6 



2 



6 



12 



27 

 + 17 



Hence, it appears that, in the month of January, an excess of 1*64 of cloud, 

 with an insignificant rainfall, accompanied an increase of - 8° of air tem- 

 perature. But in February, an increase of only 1*31 of cloud and of 2 70 

 inches of rain lowered the mean temperature 1*3°. In March, an increase 

 of 193 of cloud and of 0"54j inch of rain, on only two days, coincided with 

 a reduction of 05°. In April, an increase of only 0*21 of cloud and 191 

 inches of rain, on six days, a reduction of 1-0°; and, in May, an increase 

 of 0'62 of cloud and 1*65 inches of rain, on three additional days, a reduc- 

 tion of 1-6° of temperature. But the temperature of the ground, in which 



