necessary to excavate to the width of one hundred and forty feet, to form a race as a site for the mill houses running parallel with the river. The length of the mill race is four hundred and nineteen feet, the greatest depth of excavation sixty feet, and the least sixteen feet. The gunpowder used, alone cost the contractors upwards $ 12,000. At the upper part of this excavation were erected the head arches, three in number, which extend from the east end of the mound dam, to the rock of the bank, thus forming a continuation of the dam.

" On the west of the excavation are erected the mill houses, forming the west side of the race, which is supported on the other side by the rock, rising above it seventy or eighty feet

perpendicular. The south end of the race is also of solid rock, and the mill houses are founded on rock, so that nothing can be contrived more secure in all respects.

The race is about ninety feet in width, and is furnished with water through the head arches, which allow a passage of water sixty-eight feet in breadth, and six feet in

depth, to which the race is excavated below the overfall of the dam, and of course, room is allowed for a continual passage of four hundred and eighty square feet of water these ;

arches are on the north of the race, and the mill buildings being on the west, the water