The masonry of the dam is about 8 feet thick at the top and 65 feet at the base; it is built in a vertical form on the upstream side, with occasional offsets, and the lower face has a curved form such as to pass the water over without giving it a direct fall upon the apron at the foot; this apron is formed of timber, stone, and concrete; and extends some distance from the toe of the masonry, giving security at the point where the water has the greatest action. A secondary dam has been built at a distance of 300 feet from the masonry in order to form a basin of water setting back over the apron at the toe of the main dam so as to break the force of the water falling upon it. This secondary dam is formed of round timber, brush wood, and gravel; it may be seen in the picture directly under the bridge which extends across below the main structure. On the upstream side of the masonry of the dam, an embankment of earth is filled in, extending 275 feet from the masonry at the base, and extending from the masonry with a slope of 1 foot in 5 on the top. [Illustration: XII _F. B. Tower._ _W. Bennett._ CROTON AQUEDUCT AT SING SING.] The whole work about the dam possesses great interest, and though it be distant from the city and somewhat difficult of access, will not fail to please those who may take time to visit it. Just above the place where the dam is constructed the River had a bold turn and flowed along at the foot of a steep and rugged bank. A road passed along at the base of this hill leading to a mill which was situated at the turn of the River, before mentioned; a substitute for this road, which was submerged, has been made along the hill side passing on the right of the gate house. Enough of the forest has been cleared away to admit of the construction of the work, but the place still possesses much of its original wildness, and to see such beautiful mechanical work standing against the rude rocks,--to observe what changes have been wrought in the form of this rock to render it subservient to the purposes of the work, makes us feel that there has been a strife there; but it all shows that _art_ has gained the ascendency. The form which has been adopted for the face of the extension of the overfall is a reversed or double curve which would be easily recognized as _Hogarth’s line of beauty_: the overfall for the original dam has a plane face with a curve at the base.