21 



began in June, and with the exception of December, wiien good rains 

 tell, has lasted to the present time. Even July with 6.19 inches of 

 rain can be considered as a part of the drouth period since 6 inches of 

 rain after such a long drouth is not suiEcient to bring the cane to a 

 normal condition. 



Taking the means of lu years the drouth begins in January and ends 

 only in July. During January, February and March it does little 

 damage except as to retarding the spring plant, but the chief damage 

 is done in the months of April, May and June. 



During the past 10 years or 120 months, I should say that you 

 have had 67 dry and 5o wet months. 



Fig. III. gives the mean monthly rainfall at Arecibo during the 

 time covered by the table, aNo the mean monthly rainfall at Manati 

 beginning in January, 1899 and ending July 31, 1912. It will be seen 

 that the rainfall at Mana!;i is uniformly higher than that at Arecibo, 

 and it is probable that the curve of rainfall in the large sugar belt 

 between the two places would fall between the curves given in fig. Ill 

 though we have no data to support this assumption. 



For comparison we give in the figure the average rainfall as record- 

 ed at all the Stations of the island by the U. S. Weather Bureau for 

 the period 1899 to 1909. 



It is a fact that will probably surprise the people of Arecibo that 

 the rainfall at that place both in June and in October is the smallest of 

 the whole island, as recorded at these 44 stations. In June the average 

 rainfall was 4.24 inches, followed by Guanica with 4.37 and Santa 

 Isabel with 4.40 inches, these three stations being the only ones in the 

 sugar belt with a mean June rainfall of less than 5 inches. In October 

 the mean rainfall was 5.43 the smallest of the island, being exceeded 

 by all the stations on the southern part of the island where irrigation 

 is looked upon as a necessity. 



I have said that the summer is the critical period of the year, as 

 the greatest growth takes place then. Now the mean rainfall of the 

 summer months, June, July and August was 14.49 inches, and there 

 are no other points of the island with less than 14 inches of rainfall 

 during the summer, except Guanica with 10.39 and Santa Isabel with 

 11.89. This is exceeded by Guayama with 19.01, by Aguirre with 

 19.53, and by Yauco with 14.99 inches. I consider these facts of the 

 greatest moment in the discussion of the irrigation of the lands in the 

 vicinity of Arecibo. 



