CHAP. VIII	

ON THE SAVING OF WATER


	Every one acquainted with canals, must be sensible of the importance of saving water, and many have been the expedients resorted to for these purpose; locks being frequently constructed of only four, or four and a half, feet rise, in order to lessen the consumption of this necessary fluid; and so small a rise, on the other hand, increases the operations, and loses some time. Canals acts have also various restrictions on boats passing particular locks, unless the water flows over certain weirs, on particular ponds. The following calculations will therefore exhibit the proportions of water useful at locks, and inclined planes.

	 lock for a twenty-five ton boat is, usually, feet wide, eighty feet long, seven feet six inches wide; containing one hundred and thirty-three tons of water. A loaded boat, ascending, by pressing its weight (boat and cargo thirty tons) into the lower canal from the lack, will require one hundred and sixty-three tons of water to lock to the next ascending pond while the second boat, descending will spread her weight off the lock into the upper pond, will be one hundred and three tons.  In descending hence the average one hundred and thirty-three tons, used at every locking. Averaging empty boats in like manner, they will use also one hundred thirty three tons. To this it may be said, that two boats will pass with one lock of water; one up and one down; but this can only be the case when the two boats fortunately meet at the same lock in that precise order; but as this can be by no means common, it is not worth taking into account; I will therefore allow to every twenty-five tons cargo, considering empty and full boats, one hundred and thirty-three tons of water, which, on a trade of five hundred tons per day, would amount to two thousand six hundred and sixty tons.

	On the inclined plane the boats descending pass without water, as before  observed; it is only the ascending boats which de demand water to raise them; and they will have the advantage of a descending, boat, to assist in drawing them up: it may therefore be calculated that eight tons of water will raise four tons of cargo four tons being allowed to ensure an ample weight for the purpose, to over come friction, and for the weight of the boat itself hence, if eight tons of water are used to an ascending boat, none to a descending boat, the average is one ton of water to one of cargo : thus, in a trade of five hundred tons per day, five hundred tons of water will be used, which is not one-fifth part the quantity in demand for twenty-five  ton boats and locks; or one tenth part of water; required in locks for forty-tons; independent of leakage at gates, which is very considerable after some years wear. This saving of water will save some expense by the reduction of reservoirs  and materially facilitate all cases of descending trade from high countries; where the saving of water is an important consideration.

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