IN RAIN AND SNOW, IN THE UNITED STATES. 137 



The following table gives the monthly per centage of the mean annual rain-fall 

 obtained by dividing, in each series, the amount in each month by that of the 

 year, and shifting the decimal point. 



Monthly Per Centage of Rain-Fall. 



Month. 



(«) 



(*) 



(0 



Mean of 





1738-59 



I 841-61 



1S42-59 



b and <■. 



January- 



4.9 



5-9 



5-7 



5-8 



February 



6.5 



5-5 



5-5 



5-5 



March 



6.3 



9.0 



9.2 



9.1 



April 



4.0 



4.0 



3-8 



3-9 



May 



7-4 



8-5 



8.4 



8-5 



June 



10.5 



8.7 



9-5 



9.1 



July 



13-5 



1.1-8 



14.1 



13-9 



August 



!S-9 



16.4 



16.8 



16.6 



September 



12.4 



11. 2 



10.8 



11. 



October 



6.Q 



6.3 



4-7 



5-5 



November 



4.8 



4.2 



4.6 



4-4 



December 



6.9 



6-5 



6.9 



6.7 



The numbers of columns (a), (b), and (c) are plotted on the accompanying dia- 

 gram 4, the first by a full line, the second by dashes, and the third by dots. The 

 accordance of these lines is sufficiently close to indicate no material change. 



Diagram 4. 

 J. F. M. A. M. J. J. A. S. O. N. D. J. 



























17 

 (8 





























IS 

























14 

























= 





11 







— 



= 



E££ 

















~ 



12 









— - 







l| 





























13 



-_- 



w 





=z 











3S 











9 

 3 



7 





=£ 









^^ 















— g 



3a 



BE 





— 



s 



5 

















== 



== 



H 











In the following tables the monthly percentage of the annual rain-fall is given 

 for successive periods for two of the longest series available, and for a third station 

 selected on account of its geographical position. 



18 July, 187i. 



