38th street, was a little more than 43 miles the height above tide, at which the water would stand in the latter reservoir was 117 feet, with a minimum daily supply of about 16,000,000 gallons of running water, and 11,000,000 gallons obtainable from stored water and at a cost of four and a half millions of dollars for the whole.

The Hudson river route was traced wholly along the undulating side of the Croton and Hudson valleys, passing through Sing Sing, Sleepy Hollow and Tarrytown, and so on till it touched the line of the inland route in the valley of the Sawmill river.

The length of the route is nearly 47 miles, at an expense of $4,768,197. The plan of construction recommended, was a continuous tunnel or aqueduct in masonry as preferable both in economy and durability to iron pipes an open canal being entirely repudiated. The reasons for the preference are thus stated :

" On an aqueduct the water flows with an easy natural motion, acting upon its channel with nothing more than its own proper weight, and a friction scarcely appreciable and if by an accident its motion should be obstructed, the water having room to ;

expand, would back up and check the velocity of the approaching current without any sensible revulsion upon the sides of the aqueduct : but in a close pipe, having such a depression as would be necessary in the present instance, say 130 feet below the head, the action upon the sides of the pipe, would be about 601bs. to the inch. The water being also confined laterally, any impediment would necessarily react in some degree upon its whole volume, as far back as the nearest vent, and it should be observed that a mile of pipe contains more than 700 tons of water.