ways. In the whole year the drainage is nearly equal to one cubic
foot per second per square mile (.976), no allowance being made for
the 1.56 inches which is lost as before stated. These calculations
are based upon English experiments. Mr. McAlpine, late State
engineer and surveyor, in making his calculations for supplying the
city of Albany with water (page 22 of his Report to the Water
Commissioners), takes 45 per cent of the fall as available for the
use of the city. Mr. Henry Tracy, in his Report to the Canal Board
of 1849 (page 17), gives the results of the investigations in the
valleys of Madison Brook, in Madison County, and of Long Pond, near
Boston, Mass., as follows:

==========================================================================
| Name | Fall of rain | Water ran off | Evaporation | Ratio
YEAR. | of | and snow | in | from surface | of
| valley. | in valley. | inches. | of ground. | drainage.
----------------+--------------+---------------+--------------+-----------
1835 | Madison | | | |
| Brook | 35.26 | 15.83 | 19.43 | 0.449
------+---------+--------------+---------------+--------------+-----------
1837 | Long | | | |
| Pond | 26.65 | 11.70 | 14.95 | 0.439
------+---------+--------------+---------------+--------------+-----------
1838 | Do | 38.11 | 16.62 | 21.49 | 0.436
------+---------+--------------+---------------+--------------+-----------
Mean | | | | | 0.441
==========================================================================

"Madison Brook drains 6,000 acres, and Long Pond 11,400 acres. Mr.
Tracy makes the following comment on this table: 'It appears that
the evaporation from the surface of the ground in the valley of
Long Pond was about 44 per cent more in 1838 than it was in 1837,
while the ratio of the drainage differed less than one per cent the
same years.'

"Dr. Hale states the evaporation from water-surface at Boston to be
56 inches in a year. (Senate Doc., No. 70, for 1853.)

"The following table contains the results arrived at by Mr. Coffin,
at Ogdensburgh, and Mr. Conkey, at Syra