Medical Officers of the Army of India

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duced. On the following morning the cavity was found to be quite empty, the
surface being still moist, but with superficial cracks on it. During the course of
the forenoon 175 c.c. of water disappeared from the cavity, and the experiment
was brought to a close by one-half of the moist block, which was only supported
centrally by an iron tripod, breaking away, due to its own weight. During the
period of experiment 350 c.c. of water had disappeared from the cavity, and
only 6 c.c. from the glass vessel as the result of evaporation, leaving 344 c.c.
to be credited to the permeability of the soil. This amount does not fairly
represent the entire loss possible for the entire period, as the block was only
under observation during the hours from 7 A.M. to 7 P.M. daily and the cavity
had evidently remained empty for a long time between the experimental periods
of the two successive days.

     A second experiment of like nature was conducted as follows. The block
of soil in this instance measured 19 c. in length, 12.7 c. in breadth, and 7.1 c. in
depth, and was supported beneath on a piece of wire gauze, so as to avoid
chances of breakage like that of the previous experiment. The cavity in it and
the glass vessel used to determine loss by surface evaporation were of the same
character as in the previous case. Daily additions of water were made to the
cavity on all those days on which the laboratory was open during the hours in
which it was under observation—from 7 A.M. to noon or to 3 P.M. in one or two
instances. The experiment lasted for nineteen days, the water in the glass vessel
having totally disappeared by evaporation on the morning of the twentieth day.
The amount of water added daily to the cavity for the period was as follows:—