290 Mr. Henwood on Periodical Variations 



Collecting the annual results of this Table, itis found that the 

 cubic feet of water drawn, and rain in inches, are, 



Table III. 



From Table I. it is obvious that for the seven years under 

 consideration, the maximum of rain has been in December, 

 and the minimum in June+. 



I do not think any of the foregoing Tables afford infbrma-. 

 tion on which we can build, of the effects of rain on springs 

 rising at great depths; for in Table III. an inverse ratio be- 

 tween them seems to obtain about as frequently as a direct 

 one. Nor does this appear to proceed from any extraordinary 

 drought or flood towards the termination of a preceding year. 



The second point to be investigated is. In a given 7nine, 

 what periodical variation in the quantity of water obtains f(n' 

 any determinate increase of depth ? Seeing the difficulties with 



* For these unreported months, I have, to complete Table III., interpo- 

 lated from Table I. 



-|- Mr. Giddv, from whose resistcr the rain is taken, gives the minimum 

 rain for 18:31, 1822, 1823. 1824^, 1823, 182fi, 1827 in April, Phil. Mag. and 

 Annals, N.S. vol. iii. p. 181. 



The difference between the mean temperature of the years of these ob- 

 servations are : ^ o 



1823 mean 51- 1827 mean 51-5 



1824 - 51-5 1828 — 52-2 



1825 — 52- 1829 — 50- 



1826 — 53-5 



Giddy, Phil. Mag. and Annals, N.S. vol. iii. p. 182. 



