Ten horses are employed on the Birkenhead side for drawing wagons loaded with debris to the shaft, which, on being hoisted, is tipped into the carts and taken for deposit to various places, some of which are about three miles distant. The tunnel is lined throughout with very solid brickwork, some of which is, 18 inches thick (composed of two layers of blue and two of red brick), and toward the river this brickwork is increased to a thickness of six rings of bricks--three blue and three red. A layer of Portland cement of considerable thickness also gives increased stability to the brick lining and other portions of the tunnel, and the whole of the flooring will be bricked. There are about 22 yards of brickwork in every yard forward. The work of excavation up to the present time has been done by blasting (tonite being employed for this purpose), and by the use of the pick and shovel. At every 45 ft. on alternate sides niches of 18 in. depth are placed for the safety of platelayers. The form of the tunnel is semicircular, the arch having a 13 ft. radius, the side walls a 25 ft. radius, and the base a 40 ft. radius. Fortunately not a single life has up to the present time been lost in carrying out the exceedingly elaborate and gigantic work, and this immunity from accident is largely owing to the care and skill which are manifested by the heads of the various departments. The Mersey Tunnel scheme may now be looked upon as an accomplished work, and there is little doubt its value as a commercial medium will be speedily and fully appreciated upon completion. * * * * * DAM ACROSS THE OTTAWA RIVER AND NEW CANAL AT CARILLON QUE By ANDREW BELL Resident Engineer The natural navigation of the Ottawa River from the head of the Island of Montreal to Ottawa City--a distance of nearly a hundred miles--is interrupted between the villages of Carillon and Grenville which are thirteen miles apart by three rapids, known as the Carillon, Chûte à Blondeau, and Longue Sault Rapids, which are in that order from east to west. The Carillon Rapid is two miles long and has, or had, a fall of 10 feet the Chûte à Blondeau a quarter of a mile with a fall of 4 feet and the Longue Sault six miles and a fall of 46 feet. Between the Carillon and Chûte à Blondeau there is or was a slack water reach of three and a half miles, and between the latter and the foot of the Longue Sault a similar reach of one and a quarter miles. Small canals limited in capacity to the smaller locks on them which were only 109 feet long 19 feet wide, and 5 to 6 feet of water on the sills, were built by the Imperial Government as a military work around each of the rapids. They were begun in 1819 and completed about 1832. They were transferred to the Canadian Government in 1856. They are built on the north shore of the river, and each canal is about the length of the rapid it surmounts. [Illustration: THE GREAT DAM ACROSS THE OTTAWA RIVER, AT CARILLON.]