400 The Philippine Jowrnal of Science 1921 
Table 9, on the rainfall for 1919, submitted by the Ministry 
of Lands and Agriculture, for Nakorn Pratom, which is north 
of Ban Mai, gives a more comprehensive idea of the rainfall 
in a region near Ban Mai. 
_ TABLE 9.—Monthly report on rainfall, 1919, Nakorn Pratom, Siam. 
mm. 
January 0.0 
February 180.4 
March 26.9 
April 148.4 
May 351.4 
June : 111.6 
July 199.6 
August 197.9 
September 348.7 
October 90.2 
November 79.2 
December 0.0 
Total rainfall 1,690.0 
As indicated in the preceding tables, the average total rain- 
fall in Bangkok for ten years was 1,433 millimeters. Rain 
fell during the same period on one hundred forty-seven days 
during the year. In Nakorn Chaisri Province, at Samutsakorn 
and Supanburi, which are north of the Ban Mai region, the aver- 
age rainfall during the years indicated was 1,154.7 and 1,286.3 
millimeters, respectively. The total rainfall for 1919 at Nakorn 
Pratom, which is north of Ban Mai, was 1,690 millimeters. 
The total rainfall for those districts indicated in the Nakorn 
Chaisri region varied from 1,154.7 to 1,690 millimeters. The 
rainfall at Ban Mai would undoubtedly be between these figures, 
probably being more nearly similar to those at Nakorn Pratom. 
The reports also show that a distinct dry season is present, 
which usually starts in November and continues through the 
months of December, January, February, March, and April. 
IRRIGATION WATER 
The water used for irrigation is, except during the rainy 
season, supplied entirely from Tachin River. As explained 
elsewhere, irrigation ditches are made from the river to the 
orchards. The water is rather muddy, being filled with clay 
loam, and is reported to be salty during the months between 
January or February and July. The saltness depends upon 
the beginning and the extent of the rainy season. In the 
dry season of 1920 the water was said to have been exception- 
