" hydraulic stone masonry, connected with an earthen embankment," the embankment being two hundred and fifty feet long, sixty-five feet high at its extreme height, two hundred and fifty feet wide at the base, and fifty-five feet wide at the top, " protected on its lower side by a heavy protection wall twenty feet wide at base." On the night of the 7th of January, 1841, in consequence of a sudden and great rise in the water of the Groton, the portion of the dam comprised in the earthen embankment gave way, and the whole country below was flooded. Three bridges -- Tompkins's Bridge, the bridge at the Wire Mill, and Quaker's Bridge -- were swept away, and several mills and dwelling houses were destroyed; but, so far as was known, only two residents lost their lives. This was the only serious casualty that occurred in connection with the building of the Oroton Aqueduct. It had been earnestly desired by the people of New York that the water should be introduced into the city by the 4th of July, 1842, and this wish was realized. At five o'clock on the morning of the 22d of June, water to the depth of eighteen inches was admitted into the aqueduct from Croton Lake. A boat called the 4k Croton Maid," carrying four persons, was placed in the aqueduct, to be floated down by the stream. The water, with the boat, arrived at the Harlem River during the night of the 23d. On the 27th it was allowed to enter the receiving reservoir at Yorkville, and on the 4th of July the distributing reservoir on Murray Hill,1 both events being observed with great ceremony. The public celebration -- the grandest demonstration in the history of the city up to that time -- was held on the 14th of October.