The water continued to flow uninterruptedly through the aqueduct, from the 22d of June, when it was first let in, to the 8th of November, when it was shut off for the purpose of more effectually inspecting its condition, and the effect that had been produced by the action of the water or other cause. Previous to the time of shutting off the water, several examinations, similar to that mentioned in my report of July last, had been made by myself and the resident engineers, Messrs. French & Hastie, by means of a boat floating through the aqueduct, between the Croton Dam and Harlem River. Some unimportant defects were discovered inside the aqueduct, a short time before the water was shut off, and two small leaks ap-

CROTON AdUEDUCT. 199

peared on the outside. The next day after the water was shut off, I commenced an examination inside the aqueduct, in company with one of your Board, Mr. Ward, and the resident engineers, Messrs. French & Hastie, on their respective districts, and continued it through the entire aqueduct.

For that part on this island, our party was increased by the addition of Messrs. Ring & Birdsall, and Mr. Allen, the principal assistant engineer. On the examination we were accompanied by men prepared to attend to any work that might appear necessary and as soon as we passed over a district, they received their ;

directions, and immediately proceeded with such work as it was considered expedient to do. Some defects were discovered, the greater part of which appeared to have been overlooked in previous examinations, which now were discovered, most probably from the clean state of the masonry, after a washing of near five months there was, however, ;