Although the Croton Works were sufficiently advanced by the summer of 1842 to be put into operation, they were not entirely finished for some time. By January 1, 1844, all the work was completed with the exception of High Bridge, which was not finished until November, 1848. The total cost of the Croton Aqueduct, including land, interest on water stock, etc., amounted to about $12,000,000 (see page 311).

While the works were being finished the Water Commissioners took charge of their maintenance. Semi-annual inspections of the interior of the aqueduct were made, as recommended by the Chief Engineer, and led generally to the discovery on embankments of some small cracks in the masonry, which were repaired. The exterior of the works was constantly inspected, six stations for the "keepers" being established in 1843.

In November, 1846, one of the 36-inch pipes in the line from the receiving to the distributing reservoir burst, which was attributed to careless laying in 1841. With this exception all the work which had been constructed under the supervision of the Water Commismissioners proved to be well done.

Another change in politics having occurred, the Water Commissioners were superseded on February 8, 1843, by the former Board whom they had succeeded in 1840. The different changes in the Board of Water Commissioners made fortunately no difference in the engineer department, at the head of which J. B. Jervis remained. The original Board of Commissioners continued in office, with the exception of the year 1848 (when they were superseded by Philip Hone, John H. Williams, Nathaniel Weed, M. O. Roberts, and J. H. Hobart Hawes), until the Croton Aqueduct Department was organized under the law of April 11, 1849.

While the Water Commissioners were finishing the Croton Works the Croton Aqueduct Department (called also the Croton Aqueduct Board) formed by the Common Council (see page 44) continued the work of laying the distributing mains. By Feb. 1, 1844, 150 miles of pipes (6 inches to 36 inches in diameter) had been laid south of the Forty-second Street reservoir. The total amount of pipe laid by this Board previous to July 1849, when the Croton Aqueduct Department was formed, was about 194 miles.

A matter which soon forced itself upon the attention of the Water Commissioners was the great waste of water that was taking place. When the Croton water was first introduced the hydrants were free. The result may be readily imagined. The Water Commissioners tried various measures for stopping the waste, but without much success.

As early as 1846 the Commissioners foresaw the need of another large reservoir in the city and submitted the question to the Common Council in several reports. During thirteen days in 1846, when the aqueduct was shut off from the city for inspection and repairs, the receiving and distributing reservoirs were lowered respectively about 14 and 22 feet, although at that time there were only 12,000 water-takers.

The work of the Water Commissioners was terminated by the Act of the Legis'ature of April 11, 1849, which organized the "Croton Aqueduct Department," transferring to it all the work which had thus far been performed by the Water Commissioners and by the Croton Aqueduct Board.

CHAPTER III.

DESCRIPTION OF THE OLD CROTON AQUEDUCT.

WE shall describe in this chapter the old Croton Aqueduct, as originally constructed.* Modifications and improvements which were made subsequently will be published later.

Croton Lake (Plate 54), the "Fountain Reservoir" which supplies the Croton Aqueduct, was formed by constructing a dam across the Croton River, about six miles above its mouth. The lake is four miles long and has a width of about one eighth to one fourth of a mile. Its area contains four hundred acres, and its storage capacity for a depth of six feet (namely, to the level at which a daily flow of 36,000,000 U. S. gallons can be maintained in the aqueduct) amounts to 600,000,000 U. S. gallons.

The Croton Dam (Plate 31) was constructed across the Croton River at a point where the channel was 120 feet wide, the average depth of water being about four feet. During floods the depth of water increased to a maximum of about ten feet. At the site of the dam the left bank of the river consists of abrupt rocks, while the right bank is formed of a sandy table-land, about three feet higher than the ordinary level of the river, extending back eighty feet to a hill of sand, having a slope of about forty-five degrees.

Major Douglass located the dam originally four hundred feet further up stream, but his successor, Chief Engineer Jervis, in making the final examinations, changed the location to the site we have described in order to obtain a better foundation for the dam. At the place selected the dam had to be raised forty feet above low water (equal to fifty-five feet above its rock foundation) in order to obtain the desired amount of head. By locating the dam further up stream a site might have been found where the dam would have required only sufficient height to deflect the water into the aqueduct, but this would have lengthened the costly masonry conduit and would have rendered several important tributaries of the Croton unavailable for the city's water-supply.

On the location selected for the dam a rock foundation could only be obtained near the south bank. It was, therefore, determined to form the dam of earth, with the exception of the overflow-weir, which was to be constructed of masonry and to be located at the southern extremity of the dam. On the down-stream slope of the earthen bank a protection wall was to be built.

According to the original plans the overflow-weir was to be one hundred feet long, and to be flanked by abutments rising eight feet above its crest, but, owing to the short distance that the rock extended into the river, the length of the weir was reduced to an average of

* Plates 30 to 49, referred to in our text, are copies of the original drawings for the old Croton Aqueduct, reproduced from T. Schramke's "Description of the Croton Aqueduct," published in 1846.