300 EFFECTS OF FORESTS 



The successful essayist, Mr F. H. Jamieson, found in the observations 

 of the rainfall over extended periods, to which he had access, no 

 reason to conclude that there had been any progressive diminution in 

 the rainfall ; local oscillations alone were apparent, and the causes of 

 these it would be difficult to determine. 



" This essay gave occasion for the institution of other similar in- 

 vestigations ; and also for the establishment, through the British 

 Association for the Advancement of Science, of a number of stations 

 for the observation of the rainfall in different parts of Great Britain 

 and Ireland. And a committee was appointed by the Association to 

 give attention to the subject. 



" Mr G. J. Symons, in London, undertook the inspection of the 

 stations and the collating of the observations reported. 



" Observations made at several stations in England and Scotland? 

 of which Mr Symons was enabled to avail himself in the investigation, 

 extended back to 172G.* 



" Thanks to the observatory at Paris, we have still earlier observa- 

 tions, carrying us back to the year 1688.t 



" According to observations made in England and in France there 

 is no evidence of a diminution in the annual rainfall ; but on averages 

 of ten years there are seen differences in the quantity of the rainfall, 

 the causes of which have not yet been determined. 



* He gives iu tbe Report of the British Association for 1866, by means of registers 

 received from seventeen stations, the following data iu regard to the rainfall in England 

 in proportional measurements :— 



Period. Proportional measurement. 



1726-1735 9^"^ l 86-7 



1736—1745 78-7 > 



1746-1755 'S'^ I 83-5 



1756—1765 88-2)' 



1766—1775 103-6 \ gg.^ 



1776-1785 93-2 > 

 1786-1795 



"^■6 I 93-2 

 1796—1805 89 7 i 



f In the Annuaire meteorologiquc de V Ohservatoire physique central pour 1873, Marie 

 Davy gives the following calculation of the annnal ramfall at Paris :— 

 Period. Average in millimeires. 



1688—1700 517 



1701—1710 481 



1711—1720 465 



1721—1730 378 



1731—1740 411 



1741—1750 420 



1773—1780 540 



1781—1790 507 



