406 



THIKD REPORT — l83o. 



5. The first remark which I shall make on these results is, 

 that the diminution of the quantity of vahn received at different 

 heights above the ground, as compared with that received on 

 the ground, is very accurately represented by a simple formula 

 involving one constant, viz. the square root of the height of 

 the station above the ground, and one variable coefficient. 



Thus, m V h ■= the diminution of rain at the given height. 

 In these experiments 



V h for the Minster gauge = 

 for the Museum gauge = 



V 2 12-833 = 14-5885 



V 43-666 = 6-6080 



Taking m = 2-29, we have for the whole year. 



Ratios 

 For the 



{! 



{m 







84-9' 

 85-3 



> to 100. 



By calculation 

 By observation 

 7 coldest months 

 By calculation . 

 By observation 

 For the 7 warmest months 

 By calculation 

 By observation 

 For the 5 coldest months 

 By calculation , 

 By observation 

 For the 5 warmest months 

 By calculation , 

 By observation 



In these, which are the longest averages attainable from the 

 experiments, there is an almost exact agreement between 

 the calculated and the observed results, the 



66-5 

 66-1 



= 2-88,) 



58 81 



. 58-6 80-5 

 {m = 1-97,) 

 . 71-3 87-0 

 . 71-2 87-1 

 m = 3-06,) 

 . 55-4 

 . 56-2 

 (m = 1-75,) 

 . 74-5 88-4 

 . 73-7 89-2J 



79-8 

 79 



being jV*^- 



greatest 



error 



of three months, and, indeed, though 

 every single month when much rain fell. 



averages 



In shorter 

 less exactly, in 



may recognise the same constant relation. Thus we have 

 For the summer quarter {m = 1'43,) 



we 



By calculation . . . 79-0 90-5 



By observation . . 77-1 92-5 



For the winter quarter (m = 3-79,) 



By calculation . . . 44-6 74-7 



By observation . . 49-3 70-5 



For the spring quarter (m = 2-84,) 



By calculation . . . 58-6 81 '1 



By observation . . 59*8 80-0 



For the autumn quarter {m = 2-19,) 



By calculation . . . 68-1 85*4 



By observation . . 65-8 87*7 



> to 100. 



