ch are recommended below are ample for practical
purposes, and probably the areas to be drained by the given sizes might be
greatly increased, especially with reference to such soils as do not allow
water to percolate very freely through them.

In connection with this subject, attention is called to the following
extract from the Author's Report on the Drainage, which accompanies the
"Third Annual Report of the Board of Commissioners of the Central Park:"

"In order to test the efficiency of the system of drainage employed on the
Park, I have caused daily observations to be taken of the amount of water
discharged from the principal drain of 'the Green,' and have compared it
with the amount of rain-fall. A portion of the record of those
observations is herewith presented.

"In the column headed 'Rain-Fall,' the amount of water falling on one acre
during the entire storm, is given in gallons. This is computed from the
record of a rain-gauge kept on the Park.

"Under the head of 'Discharge,' the number of gallons of water drained
from one acre during 24 hours is given. This is computed from observations
taken, once a day or oftener, and supposes the discharge during the entire
day to be the same as at the time of taking the observations. It is,
consequently, but approximately correct:

Date. Hour. Rain-fall. Discharge. Remarks.
July 13. 10 a.m. 49,916 184 galls. Ground dry.
galls. No rain
since 3d
inst.; 2
inches rain
fell between
5.15 and
5.45 p.m.
and 1-5th of
an inch
between 5.45
and 7.15.
July 14. 6-1/2 " 4,968 "
July 15. 6-1/2 " 1,325 "
July 16. 8 " 1,104 "
July 16. 6 p.m. 33,398 " 7,764 " Ground
saturated at
a depth of 2