58 



MR. G. V. VERNON ON THE 



this entire period there were only two months approaching 

 so large a fall, viz. July 1828, 11*280 inches, and August 

 1799, 8*740 inches. (Society's Memoirs, 2nd Ser., vol. xv.) 



The summer months of 1868, 1869, and 1870 were ex- 

 cessively dry. The four months of May, June, July, and 

 August had a total rainfall of, 1868, 4*194- inches; 1869, 

 7*612 inches; 1870, 4*997 inches; the average for 77 

 years being 12*048, showing a very great falling off, espe- 

 cially in 1868 and 1870. 



In trying to trace some law of periodicity in this long 

 series of rainfall observations, I have not been able to find 

 any defined period. 



Going back to 1786, it would appear from Mr. Walker's 

 rainfall returns, 1 786-1 793, that the heaviest rainfalls did 

 not occur at the period of lowest annual mean temperature, 

 but a few years later ; but the irregularities are so great, 

 that some other method must be adopted to reduce the 

 irregularities of the temperature- and rain-curves for the 

 year : perhaps taking five years' means might enable a 

 better comparision to be made ; that is, the year itself and 

 the two preceding and two following ones in each case. 



Rainfall at Old Trafford, Manchester. 





January. 





February. 



Year. 



Rainfall. 



Differ, of 



Differ, of 



Rainfall. 



Differ, of 



Differ, of 







21 years. 



77 years. 





2 1 years. 



77 years. 





in. 



in. 



in. 



in. 



in. 



in. 



1861 



0-388 



-2-331 



— 2.1 17 



2-522 



+0-366 



+0-125 



1862 



1-896 



-0-823 



— 0-609 



0-958 



-1-198 



-1-439, 



1863 



4-425 



+ 1*706 



+ 1-920 



0-941 



-1-215 



-1-456 



1864 



1-684 



-1-035 



— 0-821 



4-027 



+ 1-871 



+ 1*630 



1865 



3-112 



+ 0-393 



+0-607 



2*357 



+ 0*201 



— 0-040 



1866 



3-252 



+ °"533 



+0747 



2983 



+ 0-827 



+0-586 



1867 



3-270 



+0-551 



+0-765 



2-930 



+ °'774 



+Q-533 



1868 



2-746 



+0-027 



+0-241 



2-114 



— 0-042 



-0-283 



1869 



2686 



-0-033 



+0-181 



4+36 



4 2-280 



+2-039 



1870 



3 -I 3i 



+0-412 



+0-626 



0-856 



— 1-300 

 3 



-1-541 j 



Means. 



2-659 



2-719 



2-505 



2412 



1 



2156 



2*397 



