The Ground Water. 
7 
which was probably due to the varying character of the soil and the 
air contained in it. On the night of July 18th a rainfall of 0.21 of 
an inch occurred, and the water plane on the morning of the 19th 
had risen rather more than 0.40 of a foot as an average for the four 
wells. No further rainfall occurred, and the weather conditions 
remained favorable for observing how long the effect of such a rain¬ 
fall would remain noticeable. On the morning of the 20th the 
level had fallen about 0.2 of a foot, and by the morning of the 22d 
it had attained the same level that it had on the 18th, prior to the 
rainfall. On the 23d it was a little lower, but rose again on 
the 24th. 
§ 14. The height of the water plane oscillated throughout the 
season, owing to the causes already mentioned, and was also influ¬ 
enced directly by irrigation of higher lying land. The record for 
1898 was a weekly instead of a daily one, and the minor changes 
due to meteorological causes were largely eliminated, and only the 
larger ones, such as were caused by drainage, or continued meteoro¬ 
logical conditions, are shown. 
« 
§ 15. There was a rise of the water table throughout the plot 
during the month of February, 1898, of about 0.5 of a foot. The 
total rainfall was only .08 of an inch. During the month of March 
there was a fall in the water level. There was a greater rainfall 
than in February, though it was still insignificant. This oscillation 
was a longer one than is due to the usual meteorological influences 
or to irrigation, besides no irrigation was being practiced at this 
season. It may have been due to freezing and thawing and to the 
consequent change in the freedom of the circulation of either the 
water or the air within the soil. 
§ 16. I supposed that the presence of the irrigation ditch near 
the east end of the plot exercised some influence upon the height of 
the water level in its immediate neighborhood. In order to observe 
the extent of this, the height of the water in two wells, A and G, 
was observed before water was turned into the ditch in the spring, 
and when no water had run in it for several months. We made 
no effort to determine whether its influence was by leakage or 
otherwise. The wells taken under observation were close together, 
A entering the gravel below the clay, while G did not reach the 
stratum of clay mentioned as separating the soil from the gravel, 
and was presumably supplied with water from the soil proper. 
Well G was not so deep as well A by 2 feet. The distance be¬ 
tween the wells was 12 feet. The water in well G usually stood 
a little higher than in well A, whether there was water in the 
ditch or not. It should be added, for a better understanding of 
the conditions, that the ground on the east side of the ditch sloped 
gently to the eastward and lay between the ditch and the drain 
