( 76 ) CHAP. X. DESCRIPTION OF THE MEDIUM PLANE FOR A SMALL AGENT, BEING A MEDIUM BETWEEN LOCKS AND PLANES. (PLATE IV.) In pursuing the small canal system, long sloping grounds will sometimes intervene, where it would be impossible to obtain a rise of sufficient importance to erect the whole of either of the machines before described, as a building, wheel, &c. would be the same as a two hundred feet ascent; the expense would consequently increase on the works, and the number of engine-men would add the expense of conveyance. Nor would it be systematic or advisable to use locks in such situations, although the lock might be so constructed as to take in ten boats at a time, five in length and two in breadth; yet the man separating his line of boats in the center, and placing them side by side to pass the next lock, and so on, when he could rise or descend but eight feet by such operation, would be a tedious work. Or if two or three boats were to pass at a time, the waste of water would be so great as might produce restriction on passing a small number of dry seasons, as before observed of canals on the lock principal, which would consequently be an interruption of free intercourse; nor could the quick trade, which I have proposed, be conducted with facility by such means. The medium will therefore exhibit the mode of mounting from twenty to thirty feet at one time, which are heights that can be obtained in any country, and probably one or two may rise, sufficient to extend a pond to such situation as will produce a plane of one or two hundred feet perpendiculars. In forming this I will suppose a rise of twenty feet, where a single plane, on an angle of about twenty degrees, is to be extended from one pond to the other; also sixty feet of such plane passing into each canal, turned hollow on entering the lower pond, and bridged on turning into the upper level. On the top and near the center of the bridge a strong framing is to be constructed, crossing the plane, in which a roller is placed similar to that under the vertical wheel in the last machine, and for the same purpose; two pulleys are also fixed to the frame in order to guide the leading chains over the center of the plane. A water wheel must then be erected near the side of the plain to create the necessary power (see the Ground Plan, on the shaft of which the leading chains are to lap, which roller may be cast in and out of gear by a lever; three hundred and fifty feet of chain must then be fixed to the roller, and pass through the pulleys over the plane. I will now suppose ten or any less number of boats ready to descend at on operation; the leading chain, making a double under the roller, is hooked to the stern of the third boat; and the wheel being put into motion it will draw the three first boats over the bridge of the plane, the other seven following: the three boats being now on the sharp angle will have power sufficient to draw out the remainder: the water is then stopped from the wheel, and the chain still continuing hooked to the boat, they will begin to descend in regular rotation; the chain, descending with the boats, will turn the water wheel backwards and answer as a break to regulate the velocity. On a man arriving at a plane the whole operation is to hook the chain to the third boat, if there are three, or the stern of one, if there is no more, and set the wheel in motion; on that boat to which the chain is hooked, mounting the bridge, the water is stopped from the wheel, and the whole line of boats begin to immediately to descend into the lower canal; during which the man attends to the break, and the time in performing this opertion, I conceive, will be as follows: Minutes Hooking the leading chain 3 Drawing the first boat out with the wheel 1 Descending the plane 1 Unhooking the leading chain and applying the horse 2 ____ 7 Hence, in a defending trade, forty tons may pass in seven minutes. In ascending, the speed will consequently be in proportion to the power of the water wheel; it will therefore be advisable to give power to the wheel in order to save time; in rising there will be three boats out of the water on a plane at a time, the plane out of water being sixty feet long; the boats and their cargoes will weigh about seventeen tons, this on a plane of twenty degrees, will be a resistance of about five tons, friction considered, perhaps six tons, to raise this I suppose an overall wheel fifteen feet diameter, and the roller on which the chain laps one foot and a quarter, or so that effect tooth on pinion, the power will increase as one to twelve, and one ton actual purchase on the wheel will raise twelve on the plane; the wheel should therefore be constructed to give one and a half tons purchase, or nearly so, and, or this purpose, should hold about two tons of water; such a wheel would perform twelve revolutions in one minute, and draw the boats forty-five feet up the plane in that time, or two hundred and seventy feet In six minutes, by which they could enter the upper canal. To perform this operation, the leading chain is continued over the ten boats in the lower canal, and hooked to the stern of the last boat, the hook of each boat is also fixed in a link of the chain , thus the ten chains, being hooked to the leading chain, the wheel is put in motion, and the whole moving forwards ascend the plane, casting off from the leading chain as they pass the bridge, and run into the upper canal, where they are immediately ready for navigation: the whole of this ascending operation may be performed in ten minutes, the descending boats being passed in seven, the average may be estimated nine minutes; hence, forty tons passing in nine minutes, three-thousand two hundred may be transferred in twelve hours. By before the calculation on the water wheel, in which a very sufficient power is allowed to raise forty tons of cargo, twenty feet would require, 228 tons of water In fort tons descending 48 tons do. ___________ 336 This will average one hundred and sixty-eight tons of water to forty of cargo, one, two, or more, boats using water in proportion; but a lock to raise forty tons would require about two hundred and sixty-tons; hence there is some water saved. It is also probable, that these machines will be constructed on the lower ponds, where water will not be so important, the supply being obtained with greater ease; the following will exhibit the expense of constructing such an apparatus: ESTIMATE FOR A MEDIUM CANAL TWENTY FEET RISE L. s. d. 180 feet plane, 1l 10s. per foot 270 0 0 Water-wheel 100 0 0 Drum-wheel, and pinion 40 0 0 350 feet chain, at 4s. per foot 70 0 0 Wheel feet 60 0 0 Two large pulleys 2 0 0 Timber and workmanship 60 0 0 _______ 612 0 0 Contingencies 10 per cent 61 4 0 _______ Total, 673 16 0 Locks for 25 ton boats, twenty feet rise 1040 0 0 Medium 673 4 0 _______ Saving 726 16 0 Locks for 40 ton boats, 20 feet rise 2000 0 0 Medium 673 4 0 _______ Saving 1326 16 0 This machine harmonizes the whole system of small canals, and fits them to every situation (where water can be found), and preserves regularity. _____________________________________________________________________________________