55 



upper one on one of the turrets of the Castle ; both have been duly 

 tested. I have been informed that in one of the balloon ascents it 

 was found the drops of rain became smaller as the elevation increased, 

 till at last the i^in was hke a mist. This would in some measure 

 account for the difference of fall, were the rule universal that a smaller 

 quantity was always collected at a high level than a low one, but, as 

 thou hast remarked, it is not the fact. In the instance in which 0-44 

 is registered at the higher level, and 2-70 at the lower referred to by 

 thee, a sUght cause of the difference might be, the snow was collected 

 in the lower one : I melted it and estimated it as rain, whUst m the 

 upper one it was blown away ; this however could only apply in that 

 one case, and that to a very trifling degree. The upper gauge is 

 under the care of the sentry on duty, who has orders to prevent any 

 one touching it. The gauges are five inches in diameter : the one at 

 the higher level has now been in its position four years ; the observa- 

 tions with it are taken once a week, or sometimes twice if there has 

 been much rain ; twice a week is as often as I am able to see it. I 

 have examined it, and find there is no leakage, so.that I am satisfied 

 with the correctness of the quantity registered. 



Thine truly, 



H. J. POULTER. 



Rainfall as indicated by gauge in 



Bussell-8treet, Dover, 30 feet above 



the sea level, 



1866 



1st mouth 



2nd „ 



3rd „ 



4th „ 



5th „ 



6th „ 



7th „ 



8th „ 



9th „ 

 10th „ 

 11th „ 

 12th „ 



Total for the year 1866 36.95 



Rainfall as indicated by gauge at 

 the top of Dover Castle, 612 feet 

 above the sea level. 



Inches. 

 . 0.68 

 . 0.98 

 . 1.47 

 . 1.51 

 . 0.85 

 . 0.97 

 . 1 — 

 . 2.13 

 . 1.53 

 . 0.60 

 . 0.57 

 . 0.44 



Total for the year 1866 12.73 



