thirty feet, the cost of a modern plant of about 1,000 H.P. would To be able to maintain speed during freshet times, an extra allowance of wheel power is made, except where the wheels are placed between two canals, and this varies from twenty-five to fifty per cent., so as an average we will allow thirty-three and a third per cent., bringing this cost to 51.50 x 1.33 68.67. To this must be added, for a sinking fund for renewals, four per cent.; repairs, one and a half per cent.; proportion of general expenses, such as insurance, taxes, interest, etc., six per cent. Wages of a wheelman, at $2 per day for three hundred and nine days a year, would be $618, and supplies, such as packing, oil, and waste, $100 per annum, or about $.72 per H.P. per annum. Total cost per N. H.P. per annum under original grants: If the water is supplied from surplus at four dollars per mill power per day, this must be increased by 4 × 309 -14=5.01, making the cost $27.63; and by a similar computation, if the water is "surplus at $2.00, the cost decreases to $16.20. We now come to the consideration of the steam side of the question, which is a more complex matter, as the cost of steam power varies greatly with the uses to which a portion or the whole of the exhaust steam may be applied. In a cotton mill where only white cloth is produced, there is very little use for exhaust or back-pressure steam, except for slashing the year around, and heating for from five to seven months; and undoubtedly the compound engine, using steam of one hundred and fifty lbs. pressure or over, and cylinders so proportioned as to allow a portion of the steam from the intermediate receiver to be used for heating, etc., is the best type. In woolen mills, and cotton mills producing colored goods, there are large demands the year around for low-pressure steam for dyeing and drying purposes; and where such a mill is driven entirely by steam, there will in winter time be use for at least three-quarters of all the exhaust steam in the various processes. If one-half of the mill is driven by water power, the engine to drive the remainder should be a simple engine, running always against a back pressure, in which case the power will be obtained at a very small cost. We will consider only these two extreme cases, and in both we will consider 1,000 N. H.P. A well-designed compound engine should, when using high steam, say of 150 lbs. gauge pressure, deliver to the shafting 93 per cent. of the H.P.; therefore, to deliver 1,000 N. H.P. the engine should indicate 1,000 1075; but, to be liberal, we will make the calculation for 1,100 H.P. The engine is to run ten hours a day on speed, and, allowing for stopping and starting, this will amount to ten and one-quarter hours per day for three hundred and nine days a year. An engine of this type should be run on one and threequarters pounds of coal per H.P., including all coal used for starting and banking, and we will take the average cost of such coal at $4.50 per long ton. This brings the cost per H.P. per annum for coal to $12.25, allowing no credit for exhaust steam used in heating, etc. If the average use of steam from the receiver throughout the year is one-fourth of the whole, the engine should be charged with about one-tenth of the heat supplied by the fuel to this one-fourth; in other words, we must credit the engine with nine-tenths of onefourth of cost of coal, which reduces the cost of coal to $9.49. Engineer at $3.00, oiler at $1.50, two firemen at $1.50 each, and one coal-passer at $1.20, will make an annual pay-roll of $2,688.30, or $2.44 per H.P. per annum. Engine-room supplies, $250 per annum, or $.23 per H.P. per annum. The cost per net horse power per annum will be eleven-tenths of this, or $21.16, which may justly be reduced by the proportion of fire-room expenses and boiler charges equivalent to the portion of the steam used for heating and slashing. The other case which we will consider is where all the exhaust steam is used at a pressure of about ten pounds above the atmos phere, for other than power purposes. Under these circumstances the engine becomes the simple non-condensing engine corresponding to the high-pressure cylinder of the compound engine; or for very large powers the compound engine may be used, the lowpressure cylinder then being under much the same conditions as the intermediate of a triple-expansion. In such an engine, single cylinder, the cost of coal per H.P. is three pounds per hour, charging all the coal to the engine; but this can be reduced to two and a half; but we will take the larger amount. If the efficiency of the boiler plant is 80 per cent., and the engine works between the limits of 150 lbs. per gauge initial pressure, and 10 pounds per gauge back pressure, it will convert about one-tenth of the total heat required from the fuel by the steam into useful work, or .3 of a pound of coal per H.P., which may be increased to .5 by the condensation in cylinder. The boiler plant for such an engine will cost more than for the first engine considered, as there is a greater weight of water to be evaporated; but this is fully offset by the decreased cost of engine, especially if the single-cylinder type is chosen. The running expenses and charges on plant will be practically the same as in the former case; but a much larger deduction from fire-room expenses and boiler charges can justly be made from the cost of power. Our cost of fuel chargeable to power is reduced in this case to $3.50 per H.P. per annum, and, other charges remaining the same, brings the total cost per H.P. per annum down to $13.25, and per net H.P. to $14.58. At the Amoskeag Mills there is a pair of Corliss engines fitted to run this way with an initial steam pressure of 100 pounds per gauge running against 10 pounds back pressure, and these engines can be started at any time and run at 1,200 H.P. without its being felt in the boiler-house, by merely turning the steam for the dyehouses through the engine. The cost in coal is so small that it falls within the daily variation from other causes, as frequently the consumption will decrease instead of increase when these engines are started. To sum up, we have the cost per net horse-power per annum : Compound engine, one-quarter exhaust, used for heater, etc.. 12.16 14.58 As the governing conditions vary in different localities, these computations must be changed accordingly; but when the increased facility of the steam-engine for close regulation of speed is weighed on the one hand, and the liability of water powers to flood, drought, and ice, I think most will decide in favor of the steam power. DISCUSSION. Prof. J. E. Denton.-When we have a chance to get right at the fountain head of the facts, as is evidently the case here, I am always provided with a few questions. At the debate last year on water-power I made a remark which, not having had time to put into the discussion, I will repeat. It was, that there has not been anything more variable in its estimates for many years back than the relative c of water and steam. You could find almost any sort of a showing by taking different statements. My remark was, that in the report of the Vienna Exposition, in summing up on water versus steam, it was stated that the cost of water-power in New England was placed at a very small fraction, something like one-fifteenth or one-twentieth the cost of steam. A few months after that report was published, a hydraulic engineer from Philadelphia stated in the Journal of the Franklin Institute that the figures given in the Vienna report were taken from the Philadelphia Water Works statistics and represented simply the cost of waste oil in running their plant; there was nothing for repairs, and there was nothing for the real cost of the water-power. I believe now that we have the exact facts here for this Merrimack system, with one exception, which is the figure for the possible deterioration of these great dams. And that is one question I wish to ask. Is the deterioration of the dams considered in the figures given by Mr. Manning? The cost is stated here of general expenses, insurance, taxes, interest and sinking fund. Does that sinking fund cover the cost of reconstruction of these great dams -which, as I understand it, were built in some cases at a large price to the parties owning them, and then passed into second hands at a cheaper price and the water rental put on the basis of the repurchase? I believe that is the case at Holyoke. I would like to ask also whether the allowance of one and threequarters pounds for compound engines is from actual measurements over a considerable period of time? As far as I can learn, a more proper allowance there would be about two pounds. I have seen a number of statements that these compound engines. in that district use generally 16 pounds of water to a horsepower. It would require an evaporation, averaging banking fires and all, of about nine pounds to bring it to a pound and threequarters. I am skeptical about any boiler being able to evaporate much over eight pounds on an average, day in and day out, includ |