Four three feet pipes, according to the calculation of the engineers, will deliver 49,843,984 gallons of water every twenty-four hours which is about the quantity calculated to be ;

delivered by the aqueduct, and nearly the average quantity running in the Croton. River. It is proposed, therefore, to insert only two of these pipes at present ; they being deemed more than sufficient to supply the city with water for many years to come. This estimate is reported in detail likewise, and amounts in the aggregate as follows :

GENERAL ESTIMATE for plan by inverted syphon and iron pipes - - $426,027 The following is a comparison between the two plans as to the estimated cost of both of them.

1st. THE HIGH BRIDGE, maintaining its established inclination over the river, $935,745 2nd. IRON PIPES, supported by a low bridge, - 426,027

Excess of expense for the high bridge, - - $509,718

In addition to the report of the chief engineer, the Commissioners directed a contracted plan of the two methods of crossing the Harlem River, to be prepared by Charles B. Pearson, Esq., an architectural draftsman, now in the employ of the Commissioners, which are herewith submitted for the inspection of your honorable body. The chief engineer expresses a decided opinion in favor of the plan by inverted syphons or pipes ; and the Board of Commissioners, after due deliberation, have adopted said plan, as, in their opinion, far preferable to that for crossing by a high bridge and inclined plane. The reasons which have governed the Commissioners in this decision, are as follows :