MARYLAND GEOLOGICAL SURVEY 



259 



months, both the greatest and the least amounts occurring in the warm 

 months; (3) that all months of the crop season are liable at times to 

 have an insufficient rainfall for the requirements of successful crop 

 growth; (4) that a period of more than four or five weeks without 

 rainfall is extremely improbable. In the eleven years from 1865 to 

 1875 there was no calender month without some rainfall. At times 

 the monthly amounts have been very small, as was the case in June, 

 1873, when but 0.41 inch was recorded, but the months of small 

 rainfall have almost invariably been preceded or followed by months 

 of abundant rains. This may be seen in the following table, in which 

 the minimum amounts of rainfall during the growing season for 

 eleven years are given, together with the amounts recorded in the 

 months immediately preceding and following: 



Amount of Rainfall 



Minimum Rainfall 



Amount of Rainfall 



in preceding month. 



Date. 



Amounts 



in succeeding month. 



5.86 inches 



March, 1866 



1.63 inches 4.75 inches. 



7.33 



April, 1871 



1.80 < 



2.67 " 



2.10 



May, 1875 



1.07 < 



< 4.70 



6.61 « 



June, 1873 



0.41 ' 



< 2.90 



4.23 



July, 1872 



1.39 ' 



' 7.22 " 



5.70 « 



Aug., 1869 



1.13 ' 



< 3.04 



1.51 



Sept., 1865 



1.07 ' 



< 4.01 « 



5.26 " 



Oct., 1874 



0.36 ' 



< 2.50 " 



The smallest rainfall within any month during this period occurred 

 in October, 1874, when but 0.36 inch fell, but there was a heavy 

 fall in the preceding month, namely, 5.26 inches, and the dry spell 

 occurred toward the close of the growing season. In June, 1873, 

 there was but 0.41 inch, but this was likewise preceded by abundant 

 rains in May, amounting to 6.61 inches, a sufficient quantity, when 

 stored up in the ground, to supply moisture to crops for a considerable 

 period. Further details of precipitation may be learned by consult- 

 ing the accompanying Table V. 



