78 H. F. Blanford — Some further results of tlie sun-thermometer. [No. 4, 



This table shews that, under a sky apparently clear, the atmosphere 

 is most and least diathermanous, respectively, in the following months 

 at the stations enumerated ; it being borne in mind that, except at the 

 Punjab stations, and, in part, at Allahabad, the months of the summer 

 monsoon are left out of consideration. 



Stations. 

 Vizagapatam. 

 Sironcha, 

 JBomhay. 

 Jessore. 

 Hazaribagh. 

 Allahabad. 

 Sirsa. 

 iPeshawar. 



Least. 

 April, May. 

 March. 

 May. 

 April. 



Deer., Feby., March. 

 June. 

 June. 

 July. 



Insolation. 

 Gbeatest. 



November, December 



October, November. 



February. 



October. 



October. 



February. 



March, April. 



February, March. 



The results of the laboratory investigations of Professor Tyndall, 

 as well as Mr. S. A. Hill's discussion of Mr. Hennessey's actinometric 

 observations at Mussooree, obviously suggest the vapour constituent of 

 the atmosphere as the variable element on which the actinic absorption 

 of the atmosphere, may be expected to depend. And, on comparing the 

 above results with the monthly averages of vapour tension, humidity 

 and cloud proportion, (the last being regarded as an index of the relative 

 humidity of the higher atmospheric strata), this expectation is confirmed 

 in the case of the two coast stations Bombay and Vizagapatam ; at least, 

 with a near approximation. The results of the comparison in the case 

 of these two stations are as follow : (Table IV, A). The maximum phase 

 of each element is indicated by an (*) the minimum by a (f). 



Table IV. — Comparison of the annual variation of insolation tempera^ 

 ture on clear days with those of vapour tension^ relative humidity and 

 cleud proportion. 



A. — Coast stations. 



-i 





Jan. 



Feb. 



Mar 



April. 



May. 



Oct. 



Nov. 



Dec. 





Insolation 



301 



29-2 



260 



24-3t 



24-4 



281 



305 



30-7* 



t 



Vapour Tension .... 



•586 



644 



754 



•853 



•916* 



•818 



•663 



553t 



S 



Relative Humidity . . 



65 



64t 



66 



68 



69 



72* 



66 



64t 



> \ 



Cloud 



1-74 



144t 



1-76 



2-66 



418 



450* 



3-23 



2 31 



Insolation 



Vapour Tension . . 

 Relative Humidity 

 Cloud , 



59-0 

 •583t 

 70t 

 1-60 



600* 

 •616 

 70t 

 138t 



58 8 I 57-8 



•720 .822 



73 75 



1-91 2^38 I 



56-7t 



582 



575 



•886* 



•850 



•700 



75 



81* 



71 



4-12 



4^42* 



2-22 



58-6 

 •627 

 70t 

 1-76 



