[D8938ABI], Letter from William Dennis Marks to Thomas Alva Edison, July 29th, 1889



In response t your request, per Mr. Tate, I make the following report to you on the relative cost of 1,000 H.P. in boilers, engines, dynamos, pumps, steam piping, heaters, injectors, tanks, water piping, blast piping, blowers, chimney, etc.####I find in round figures that the cost of these exclusive of electrical connections aggregates in the neighborhood of $100.--a horse power, or $100,000.--for 1000 H.P.####I find also that the cost of a storage battery of plain lead plate 1/8 " thick and capable of working without repairs for three years under such abuse as over-charging, complete short circuiting, and the various accidents that befall a battery in praacftical use, requires about 400 pounds of lead, which, as the ruling price of lead is 5 cents per pound, we can estimate in its manufactured state at 7 1/2 cents per pound, or $80.--per cell having a surface of 120 odd square feet, a discharging capacity of 420 ampere hours, and reckoning the E.M.F. at 1.85 volts, a capacity of 777 watt hours or 1.04 horse power hour; 1,000 of these cells would in round figures furnish 1,000 H.P. hours, and would cost for lead $30.--for box and acid $5.-…..total $35.--each. But, if it was intended that this storage station should supply 1,000 horse power or 12,000 lamps for 4 hours, the total cost would be 4 x 35,000-----------$140,000####This is assuming that bur 3 1/2 ampere hours can be gotten from a square foot, which is a very low estimate.####It would be necessary to form this battery by some of the quick alkaline methods.####B.de Montaud, Civil Engineer, No.78 Rue d' Allemagne, Paris, has done a good deal of work in its solution, and his work has furnished me with the basis of my suggestions to you.####Should it prove that there will be little or no repairs for three year on these lead batteries, the difference in cost $40,000.--between running boilers, engines and dynamos, and the attendance required by them, would be compensated to a considerable extent by the low cost for attendance and repairs of a storage station.####Should you desire me to go into this matter more in detail I shall be pleased to give it a very careful study, and furnish you with designs on the large scale which I have suggested.####Yours vvery truly, Wm. D. Marks####Engineer-in-Chief.####[name mentions: B. de Montaud, Thos A. Edison, A.O Tate, Wm. D. Marks, Edison General Electric Co.]









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[D8938ABI], Letter from William Dennis Marks to Thomas Alva Edison, July 29th, 1889

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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University