312 Royal Society : — Ilev. G. G. Hodgkinson's Actinometrical 

 Comparison of Results, Summit of Mont Blanc and Chamonix. 





M. Blanc. 





Ratio of 





Actinome- 





Ratio of 





Actinome- 



Chamonix. 



actinome- 





ter (K) re- 



Chamonix. 



actinome- 



Apparent 



ter (K) re- 



Actinom - 



ters, Mont 



Apparent 



duced to 



Actinome- 



ters, Mont 



time. 



duced to 



ter (A). 



Blanc and 



time. 



actinome- 



ter (A). 



Blanc and 





actinorne- 





Chamonix. 





ter (A). 





Chamonix. 





ter (A). 















h ra 









h ra 









8 27 





812 





9 34 



996 







8 30 





799 





9 35 





811 



1-228 



8 33 





794 





9 37 



998 







8 36 





805 





9 38 





809 



1-234 



8 39 





803 





9 40 



1002 





1-219 



8 42 





800 





9 41 





822 



8 45 





803 





9 44 





835 





8 48 





802 





9 47 





838 





8 51 





791 





9 56 



992 







8 54 





797 





9 59 



988 







8 57 





795 





10 2 



993 







9 





807 





10 5 



994 







9 11 



955 



821 



1-163 



10 8 



1001 







9 14 





807 





10 9 





826 



1-212 



9 17 





800 





10 11 



1014 







9 24 



995 







10 12 





841 



1-206 



9 27 



994 







10 15 





853 





9 31 



993 





1-244 



10 21 



1010 







9 32 





798 



10 24 



992 















10 32 





814 





Meteorological Observations on summit of Mont Blanc and at Cha- 

 monix, July 14, 1866. 



Mean 





Mont Blanc. 



Chamonix. 









Barometer 







time. 



time. 





Thermo- 



Thermo- 



corrected 



Thermo- 



Thermo- 







barometer. 



meter 



meter 



and re- 



meter 



meter 





• 



(dry). 



(wet). 



duced to 



(dry). 



(wet). 













S2 3 F. 







h m 



h m 















8 30 



8 25 









26-90 



69 F. 



57 F. 



8 40 



8 35 



16-86 



22 F. 



Below 20 









9 30 



9 25 



Boiling- 









72 F. 



59 F. 



9 45 



9 40 



point = 

 184°-5 F. 



22-5 F. 



Below 20 









10 45 



10 40 









75 F. 



58 F. 



11 



10 55 





24 F. 











2 5 



2 











82 F. 



63 F. 



Appendix (A). 

 Description of the Actinometer. 

 The actinometer employed consists of a thermometer with a sphe- 

 rical bulb one inch in diameter, and a tube, of which an inch and a 

 half next the bulb is, for a reason which will presently be apparent, 

 left unsealed. The succeeding ten inches is made to represent, as 

 nearly as may be, the range from 40° F. to 45° F. At eleven inches 



