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by manual labour or by hydraulic appliances. The latter would be preferable, as the force required to lift ordinary draw-gates would be considerable. Assuming the gates to be sft. wide, and depth of water 18ft., the pressure on the face of each gate would be 22-6 tons; however, centre verticalhinged balance-gates would be much more easily worked than draw-gates, and equally as cheaply constructed; but this is a question that need only be taken into consideration when the construction of the locks are determined on. The present question at issue is, "Is the scheme practicable ?" Several moveable weirs have been constructed in rivers in different parts of the world on designs somewhat similar to that required for the locks in question —as, for instance, the drawdoor weir on the Thames River at Teddington, in the rivers in Northern India, on the Seine below Paris, and elsewhere; the question, therefore, of the feasibility of constructing locks at the outlets of the lakes is one that can be answered in the affirmative. The work can be done, and the lakes are of sufficient area to admit of their outlets being closed up for short periods without doing any damage to property alongside their shores; but such works would entail the expenditure of a very large sum of money. Haivea Lake. The Hawea Lake comprises an area of forty-eight square miles. At the outlet there is a good site, with rock-foundations and abutments at each side, for the construction of a lock. The water could be raised 10ft. above the level at the time of my visit. At the place where a lock could be constructed the width of the river is 100 ft., having an average depth of sft., and a velocity of 6'4ft. per second, which gives a discharge of 3,200 cubic feet of water per second. In checking this discharge measurements and soundings were taken at the bridge, about 20 chains below the outlet of the lake, the width of the water in the river at this point being 84ft., having varying depths, which were taken at certain distances along the bridge. The volume of water by measurement at this point was 3,216 cubic feet per second; therefore 3,200 sluice-heads may be taken as a close approximation of the quantity discharged at the time of my visit. This discharge would, if dammed up, raise the surface of the Hawea Lake 2-6 in. in the twenty-four hours, and it would take about forty-six days to raise the surface of the water 10ft. The width of the lock from abutment to abutment would be about 300 ft., and the width in water-way in the gates would require to be about 125 ft. Assuming each gate to be sft. wide, there would be twenty-five gate's, each sft. by 15ft., which have a pressure against them when the water was up to the full height equal to about 18-8 tons. Taking the whole width of the structure between the outside piers as 200 ft., it would have to be capable of resisting a pressure of about 728 tons. Wanaka Lake. The Wanaka Lake comprises an area of seventy-five square miles. There is no natural site with rock-foundations and abutments for the construction of a lock at the outlet of this lake. The banks on each side are apparently comprised of shingle, but it is possible that rock might be found on each side on excavation. The bed of the outlet is sand and shingle, having a great depth of water, especially on the Pembroke side of the Clutha River. The width of the outlet near the head of the river is 330 ft., but possibly the best site for the construction of a lock would be about a mile down the river, towards Albert Town, where it is said that there is a rock bar across the bed of the river ; however, in either case a considerable excavation would have to be made in order to provide for sufficient width of water-way, which would have to be, inclusive of piers and divisions, about 660 ft. Until a site was selected, and tests made as to the nature of the ground, it would be difficult to tell what the total width of the structure would be in order to get good abutments. If it had to be constructed at the outlet it would require piling and concrete foundations across the bed of the river. It was difficult to measure the volume of water at the outlet with any degree of accuracy with the time at my disposal; but I measured the width and depth of the river at Albert Town punt, where it has a regular depth all the way across, and ascertained the velocity of the current by a float. The width of the river at this point was 265 ft. 6in., having an average depth of Bft. 6in., and flowing at a velocity of 200 ft. in thirty-three seconds, which is equal to 606 ft. per second. This gives the volume of discharge as about 13,676 sluice-heads ; deducting from this the discharge from the Hawea Lake —namely, 3,200, it leaves the discharge from the Wanaka Lake as 10,476 sluice-heads, or the same number of cubic feet per second. The surface of the water in this lake could be raised 6ft. above the level at the time of my visit without doing any damage to property. Taking the volume of discharge as 10,476 sluice-heads, if this was dammed up it would raise the surface of the water in the lake 5-15 in. in every twenty-four hours; it would therefore take nearly fourteen days to raise the surface of the lake 6ft. There are other elements to be taken into consideration in connection with both this lake and Lake Wakatipu, and that is the force of the wind, which has a great deal to do with raising the surface of the water in the lake; and from information received from Mr. R. McDougall, a very old resident at Pembroke, the surface of the water in the lake was on one occasion fully 10ft. above its level at the time of my visit, and if such were to occur, and locks placed at the outlets, no doubt the parties having houses and property on the flat would attempt to lay claims for compensation; at all events, it proves that in the event of locks being constructed a larger water-way would have to be provided for than the natural opening. The whole structure would have to be substantially constructed so as to insure its durability. The pressure which it would be subjected to, supposing the lake stood at 6ft. higher level, would be about 2,282 tons. Wakatipit Lake. The Wakatipu Lake comprises an area of 114 square miles. There is a good site for the construction of a lock at the outlet of this lake into the Kawarau River, having rock-foundations across the bed of the river, also rock-abutments at each side. The width of the outlet at the