407] F. §. Holmes 209 
clay loam, and the third was a mixture, of equal parts, by 
volume, of the other two. Pots of each kind of soil were 
equipped with auto-irrigators having respectively one, three 
and five porous cups, thus giving nine combinations. The 
containers were tinned sheet-metal cylinders approximately 
15 cm. in diameter and 17 cm, in height. The porous cups 
were evenly distributed within the soil mass, when but one 
was used it occupied the center. A mercury tube was so ar- 
ranged that all water entered the soil against a pressure of 
from 5 to 6 cm. of a mercury column. Evaporation was pre- 
vented by sealing covers on the containers with plastiline. 
The cylinders were filled to a uniform depth of 16 em., an at- 
tempt being made to secure as uniform packing as possible 
throughout the entire series. 
Weighings of the containers were made at intervals of two 
or three days, for the first twenty days, and thereafter at 
weekly intervals, to determine the rates at which water was 
being absorbed and to approximate the moisture content of 
the soil. Approximately three-fourths of the water taken 
up by the loam and by the sand-loam: mixture occurred dur- 
ing the first ten days, but the sand took up only about one- 
half of its total amount in the same period. Approximate 
equilibrium of the soil moisture content was reached in about 
seventy-five days, in the case of the loam; in about eighty 
days in the case of the mixture; and in about ninety days in 
the case of the sand. The number of porous clay cups em- 
ployed seemed to have no influence upon the length of time 
required for the attainment of equilibrium by either the loam 
or the loam-sand mixture. With the sand, however, the 
number of cups appeared to influence the length of this time 
period. With three cups equilibrium was reached sooner than 
with one, and with five sooner than with three. 
When the weighings of the cylinders and observations on 
the water reservoirs showed that the soil had ceased to absorb 
water, the cylinders were opened and samples were taken for 
soil-moisture determinations. Two 1-cm., full-depth cores 
were taken from each container, one core from -as near a cup 
14 
