( 82 ) CHAP. XI. OF CONSTRUCTING AQUEDUCTS. Having exhibited the mode of passing the boats to and from the different ponds of canal, and shown the great difference in expense between the method described, and locks; the next consideration of the most importance, in prosecuting navigations, it the expense of constructing Aqueducts. In seeking to extend the benefit of water-carriage, and pass to certain towns or districts by the nearest route, wide and deep valleys will frequently present their extensive chasms, and seem to exclude connection,; which, on the lock principle, would, in numerous instances, be the case; for if I suppose a valley two hundred feet deep, and six hundred yards wide, what country could produce a trade to pay for an aqueduct in such a situation? That there are an infinite number of similar situations, where it would be desirable to pass in order to open a newer communication, I conceive no one will deny; and in such a situation, 200,000l would not pay the expense of an aqueduct. To lock down and up would be equally difficult, considering waste of water and loss of time; and, if practicable, to go by a circuitous rout, the distance might be so great as to raise the material to the expense of land carriage, consequently, the happy except of a water intercourse between such districts, could never be experienced on the lock system. But, to surmount these difficulties, and open up an easy communication, see Plate VI. representing the conjunction This is simply two single inclined planes in conjunction, expanding from hill to knoll, and binding the two countries in the bonds of reciprocity. Each plane extending down the side of the hill, they are united at the bottom by a double plane, in the from of a long oval, on which the boats pass each other . See the Ground Plan. On the ends of the oval, there are guides working on a bolt, which move from side to side of the plane alternately, as the boats pass, which prevents the two boats ever landing on one plane, or interrupting the passage of each other. In this the operation at top is exactly the same s the single inclined plane; but at bottom a man is placed where the boats are to pass; and on each engine letting down a boat, the man at bottom removes the chain from one boat to the other, and giving the signal to the men above, each draws up his opponent's boat; thus they are transferred across the valley to the different ponds of canal. In performing the operation on the single plane, six minutes is allowed to pass two boats, one up and one down, in doing this, the time will not be much more; for each man at top working at the same time the same operation the two boats will be moving down the planes towards the center at the same time, where the man can transfer the chains in nearly the same time that he could hook a boat; but as they may not all work regularly at the same time, I will allow eight minutes to each operation amounting to one ton per minute, or seven hundred and forty in twenty-four hours; a quantity sufficient to show, that if each operation was much longer than here estimated, yet a very important trade may be performed. In the climate of expenses, each man letting letting down and raising a boat for three pence,; and the man at the bottom transferring the chains for three pence on two boats, would amount to one penny and a fraction per ton; but considering empty with full boats, I will allow one penny half penny per ton for passing this apparatus, such I conceive adequate to every contingency; and the following will exhibit the probable expense of constructing the machine. ESTIMATE FOR A CONJUNCTION TWO HUNDRED FEET HIGH, SIX HUNDRED YARDS IN WIDTH First Half L. s. d. 380 yards inclined plane, 4l. 10s. per yard 1710 0 0 67 yards tub pit, 4l 15s per yard 318 0 0 320 yards sough, 15s. per yard 240 0 0 Vertical wheel 50 0 0 1000 feet chain, at 2s per foot 100 0 0 Wrought-iron tub 60 0 0 1,400 feet tub anf balance chains, at 4s. per foot 280 0 0 Drum-wheel 100 0 0 Pinions, boss, and levers 60 0 0 Centrifugal fans 60 0 0 Building and timber to support the works 200 0 0 _________ 3178 0 0 Second Half, 3178 0 0 _________ 6256 0 0 In passing place, 60 yards plane, 4l. 10s. per yard 270 10 0 Culvert or bridge 200 0 0 _________ 6826 0 0 Contingencies 10 per cent 682 0 0 _________ Total, L. 7,508 10 0 As the whole water used in raising the boats will descend to the valley, and be lost from the canal, it will amount, on a trade of five hundred tons per day, to about two thousand tons waste, equal to about eight lockings for forty-ton boats, which passing from the upper ponds of canal, where water is scarce, to the lower, where it is of little importance, water being there more abundant from various sources, is similar to the above waste. In constructing the conjunction, there is also the advantage of gaining height; one plane may rise higher than the other is necessary, and thus gain any number of feet which the ground will admit of, yet perform the transfer with the same facility, and if one pond must be replenished with water from the other, a pipe may be laid along the side of the planes for that purpose. Having exhibited the difficulties which may be overcome by this machine; I hope criticism will pardon my attempting to display the advantage which will accrue, if I estimate the probable expense of a canal with seeing the ground. But suppose it necessary to supply a town with the very necessary article of coal, the works distant ten mile with such a valley, and two hundred feet rise intervening; in this, which is rather a difficult situation, the expense would probably be as follows: L. s. d. Constructing the conjunction 7508 10 0 Two single inclined planes, 100 feet rise each 3056 6 0 Reservoir 3000 0 0 Land, 5 acres per mile, 100l. per acre 5000 0 0 Cutting. planting quick, &c, 500l per mile 5000 0 0 Bridges and culverts, 300l. per mile 3000 0 0 __________ 26564 16 0 Contingencies, act of Parliament, &c. 2656 9 7 29,221 5 7 __________ The interest of 29,221l. 5s. 7d. at 5 per cent per ann. 14611 1 3 On this canal, 50 tons per day, allowing 280 working days, and 3d. per ton per mile, would produce, per annum, 1750 0 0 Which, after paying the subscribers 5 per cent. leaves for agency and repairs 288 18 9 Thus, on a trade of no more than fifty tons per day, the subscribers would have a fair prospect of receiving 5 per cent: And although three pence per mile may appear high tonnage for canals, yet they arrive at town for the following sum per ton, carriage: s. d. Three pence per ton per mile to the company 2 6 Passing two inclined planes 0 2 Passing the conjunction 0 1 1/2 Boatman 6s. 8d. per day, or o that amount, conveying 10 loaded, and returning 10 empty boats in one day 0 2 _______ Total per ton for ten miles 2 11 1/2 Which could not be conveyed for less than 7 6 _______ Hence saving to the inhabitants per ton 4 6 1/2 Which might produce a further saving as the trade increased; in which case the tonnage should be lowered: when one hundred tons per day is performed, and the company receive more than 10 per cent. the tonnage by the act should be reduced, on rude produce, to 2d. per mile. When one hundred and fifty tons per day is performed, and the company receive more than 15 per cent the tonnage or rude produce should be three half pence per mile, but never lower by the act; competition among canals will regulate the carriage of course, and competition will be a benefit to the country. It is therefore good policy in Parliament, to allow ample tonnage, that subscribers may have a prospect of a return on a small trade which will be an encouragement to speculators: the reduction of tonnage on rude produce to be governed by the returns; but on merchandise, to stipulate for a certain sum, which the proprietors might reduce as policy dictates. And thus canals will be extended in every direction, in consequence of the best of all encouragement, that of receiving a fair interest on a small trade; and the prospect of this interest increasing to a very important return of wealth from a small capital.