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X. — The Rainfall of Cornwall, with Ohservations on the Flow of 

 Streams. — By H. Michell Whitley, Assoc. Inst. 

 C.E., F.G.S. 



Read November 6th, 1875. 



Part I. — Eaineall. 



THE amount and fluctuation of tlie rainfall of a district, associ- 

 ated as it is with the climate, is a question intimately con- 

 nected with the welfare of its inhabitants, and whether we consider 

 its bearing on the water supply of the towns, or its effects on the 

 nature of the cultivation of the country districts, it appears 

 desirable that it should be ascertained as correctly as possible. 



For some years past numerous rain-guages have been estab- 

 lished in various parts of the county, some have been at work 

 for short periods only, whilst the register from others is still 

 continued, and in some cases extends over a considerable length 

 of time. It is my purpose in this paper to collect and tabulate 

 these various observations in a convenient form for reference, 

 and from them to deduce the Mean Annual Rainfall in the different 

 districts of the County — and to add some data on the proportion 

 of rainfall which flows off the surface by streams. 



The first observations taken in Cornwall of which I believe any 

 record is published, are those by Dr. Borlase for Ludgvan, from 

 the years 1767 to 1771, given by Dr. Dalton in his paper submitted 

 to the Manchester Literary and Philosophical Society in the year 

 1799. "^^ The aniou.nt of rain for Ludgvan is there given as 41-00 

 Ins., and Dr. Dalton adds " Another place in Cornwall 29 Ins." 

 but gives no further particulars. Mr. Symons adds the year 

 1762 to Dr. Dalton's five years. f The next measurements are 

 those of Mr. Giddy, taken at Penzance between the years 1821 

 and 1828. J: Beardmore in his Synopsis of British rainfall gives 

 Penzance 1825 to 1833, Mean Rainfall 43-10 Ins. at a height of 



* Transactions Manchesttr Literary and Philosophical Society, Vol. 5, p 148. 

 t Reports British Association 1865, p 190. 

 X Reports British Association, 1865, p 196. 



