300 EFFECTS OF FOEBSTS 



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 cpllating 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 1726.* 



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

 tions, carrying us back to the year 1688.+ 



" 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 in the Report of the British Association for 1866, by means of registers 

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

 in proportional measurements : — 



Period. Proportional meaiurement. Period. Proportional mesiswemmt. 



1726-1735 9A-6)gg.;^ 1806—1815 94 6) gg.3 



1736—1745 78 7) 1816-1825 103-9i 



1746-1755 '^filgj.j 1826-1835 10''3].100-8 



1756—1765 88-2X 183G-1845 100-2J 



1766—1775 10361 gg.^ 1845-1855' 100-6 1 gg, 



1776-1785 93-2' --- - *" 



1786-1795 95 6 , gj.j 



1796—1805 89 " 



t In the Annuaire mitiorologique de V Observatoire physique central pour 1873, Mari^ 

 Davy gives the following calculation of the annual rainfall at Paris :— 



Period. Average in millimiires. Period. Average mm, 



1688—1700 517 1791-1798 413 



1701—1710 481 1804-1810 518 



1711—1720 465 1811-1820 496 



1721—1730 378 1821—1830 514 



1731-1740 411 1831-1840 507 



1741-1750 420 1841-1850 529 



1773—1780 540 1851—1860 520 



1781-1790 507 1861—1870 493 



Igg.^ 1845-1855' 100-6 ■(, 



> 1856—1865 26-3 J ' 



