124 TRANSACTIONS OF THE [FEB. 18, 
the character of a lake reservoir than would any of the local 
basins which it was proposed to establish in different parts of 
the water-shed. These would be shallower and warmer, and 
therefore would contain a greater amount of animal and vege- 
table life. On the other hand, the construction of the Quaker 
Bridge dam presented serious engineering difficulties; much of 
its foundation must be laid in the bottom of the ancient channel 
of Croton River, one hundred feet below the present water-sur- 
face. The engineers tell us this could be done, but it would be 
at a great cost. It would also be necessary that the dam should 
be made very strong, since much of it would be a wall one 
hundred and forty feet high and one which must resist an 
enormous pressure, especially at the time of floods. This also 
the engineers tell us could be accomplished, but it would cost 
money. 
It has been suggested that a structure of this kind might be 
destroyed by an earthquake like that of Charleston, and such as 
may possibly affect the country about New York at any time. 
The chances of such an event may, however, be considered small; 
and if properly constructed with a heavy embankment above 
and an equally heavy apron below, the dam would be for the 
most part subterranean, and only the upper part would be likely 
to be thrown down; and any earthquake which would destroy 
the dam would so completely destroy the city that the loss of 
the dam would be of comparatively little consequence. 
The construction of a number of local reservoirs would prob- 
ably cost less than one great one, near the mouth of the Croton, 
and they might be built in succession, as needed; so their cost 
would be distributed over many years. The suggestion of Mr. 
Potter, that when the supply furnished by the Croton basin 
became inadequate the head waters of the Housatonic could be 
utilized, is an important one, and with the rapid growth of the 
city must before many years be adopted. The wants of a 
population of four or five millions must be considered, but 
fortunately they need not be provided for at once. As the 
water consumption increases it can be supplied by an extension 
of our aqueduct system to the upper part of the Housatonic 
basin or even to the Adirondacks. 
