In the course of examinations which were made to determine sources whence water could be obtained, questions of deep importance presented themselves in regard to the source to be relied upon for a supply, also in reference to the plan which should be adopted for conducting the water to the city.

It was of so much importance to the city that the supply should be such as not only to answer the present purposes, but be adequate to the future increased demands, and that the quality of the water should be unquestionable, that it

became necessary to extend the examinations over every watered district in the vicinity, in order to judge of the comparative merits of different sources. The Engineers who were employed, traversed the country, gauged the streams, reported their supply, the quality of the water, and plans which might be adopted for conveying it to the city.

It was a field for the exercise of the talent and research of the Engineer : in resorting to a distant stream for a supply, any plan which he might propose for conveying the water, would encounter obstacles requiring skill and ingenuity to

overcome. He would find it necessary to build up the valleys, pierce through the hills, and span the waters of the arms of the sea which embrace the city and make it an island. Structures would be required, which, in their design, would find no parallel among the public works of this country, and in forming plans for them he might study with advantage, the works constructed for similar purposes by the Ancient Romans. The examinations embraced all the sources from which a supply of water might be obtained in the neighboring counties of Westchester and Putnam ; giving a comparison of the different streams in regard to their elevation, their capacity, and the quality of the water.