to present the estimates in the complete state in which they now appear. I am sir, very respectfully, your most obedient servant, M. C. MEIGS, Lieutenant of Engineers, in charge of surveys, &c. Gen. JOSEPH G. TOTTEN, Chief Engineer. Extracts from a letter from Prof. John Torrey, M. D., to Lieut. Meigs. "All the waters are soft and very good, both for washing and for drinking. There is no hurtful ingredient in any of them. The quantity of free carbonic acid which they contain is from two to three cubic inches to the gallon. Of solid matter left by evaporation, there was in no case more than a fraction over five grains to the gallon. Of this residual matter, the quantity of salts soluble in water did not exceed one grain, consisting chiefly of chlorides of calcium, sodium, and magnesium. "The salts insoluble in pure water (and undoubtedly held in solution in the waters examined by an excess of carbonic acid) were the carbonates of lime and magnesia-the quantity varying in the different waters from three to four grains in the gallon. “Of sulphates, we could only find a trace. Organic matter was present, but less than half a grain to the gallon. "Our chief difficulty in analyzing these waters was their purity, and the small quantity submitted to us for examination. Several of the constituents were only to be estimated approximately, from the minute amount of them existing in the waters. "Finally, I would say that the waters sent us exhibited a great uniformity of composition, and are all sufficiently pure for drinking or for manufacturing purposes; indeed, they are superior to the Croton water, according to the analysis of Professor Silliman. 'I would not be willing to undertake a new analysis, except on a larger quantity of water, or, what would amount to the same thing, on a quantity of solid matter obtained by boiling down at least twenty gallons of each variety of the water to be examined. "We have now our processes so perfected that a re-analysis would take comparatively little time. "I am, dear sir, yours, respectfully, "JOHN TORREY." NOTE.-The waters submitted to Prof. Torrey for examination were— A. Two gallons taken from the Potomac at the Great Falls. B. Two gallons taken from the Potomac at the Little Falls. C. Two gallons taken from the Potomac 300 feet below Mason's foundry, above Georgetown, at high tide, 2 p. m., November 6, 1852. D. Two gallons taken from the Potomac 400 feet below Mason's foundry-taken at low tide, 8 a. m., November 6, 1852. E. One and a half gallons taken from Rock creek, on Hoyle's farm, November 25, 1852. M. C. MEIGS, Lieutenant of Engineers. PHILADELPHIA, December 8, 1852. DEAR SIR: Your favor of the 30th ultimo came to hand only a few days ago, having been absent from Philadelphia. Before leaving the city, I sent to your address two new estimates of cost: 1st. Of two Jonval turbines, on a horizontal shaft, capable of lifting, with one pump, 5,000,000 gallons in 24 hours; 2d. Of two sets of above-named turbines, capable of lifting, together with two pumps, 10,000,000 gallons in 24 hours. Since the receipt of your favor, and my sending you the above, I had a conversation with Mr. Frederick Graff, and also reflected more fully on the project of the whole apparatus, and found it necessary to present you with a new estimate of cost, which, of course, would annul the one forwarded to you under date of December 1. Following Mr. F. Graff's information, one-tenth of the amount of theoretic labor ought to be allowed as loss at the pump's feeding, under a head of 8 to 10 feet. On account of the immense size of pump and the pressure thereon, I found that it would not be safe to make the thickness of metal, at all parts of the pump, less than 3 inches, and to have an air-vessel of at least three and a half times the volume of the one at Fairmount, which is 3 feet inside diameter, 10 feet high; that it would be prudent to calculate only on 20 hours' labor in a day on an average-thus leaving 4 hours for oiling, cleaning of machinery, chances of getting out of order, and packing of stuffing-boxes, &c., as the turbine-wheel at Fairmount could only have this average: the wooden wheels at Fairmount having only an average of 12 hours a day. I found, also, that it would not be advisable to go above the speed of 146 feet per minute with the pump. I read, also, in your favor of the 30th ultimo, "and the pump made of such size as, if working without loss, to discharge 6,000,000 gallons a day, and the wheel should have the necessary horse-power to raise this quantity." Then, taking the Fairmount pump as standard, it would require 285 horse-power to raise 6,000,000 gallons 200 feet high. 40 horse-power would lift 1,700,000 gallons 100 feet high in 20 hours. 141 horse-power would lift 6,000,000 gallons 100 feet high in 20 hours. 282 horse-power would lift 6,000,000 gallons 200 feet high in 20 hours. The pump capable of lifting the above amount in 20 hours, at a speed of 146 feet per minute, and, say, 9 feet stroke and 7 strokes per minute, would require to be of a diameter of 30 inches. Area x speed per minute × 60 × 20 hours = 880,000 cubic feet, or 6,600,000 gallons, theoretical. 5 square feet X 146 × 60 × 20 = 880,000. = 5 square feet 720 inches, or a circular area of 30 inches diameter. In the hope that the above will be of interest to you, I remain yours, very respectfully, EMILE GEYELIN. P. S.-Shall I make you a plan of this project to lay before the committee? Pumping apparatus for Washington and Georgetown water-works—estimate of cost. 1st. Of two Jonval turbines together, of 285 horse-power, on a horizontal shaft, operating under 30 feet fall, all complete in themselves. 2d. The necessary gearing to transmit said power to a double-acting pump, at a speed of 7 revolutions per minute. 3d. A double-acting pump, 30 inches diameter, 9 feet stroke, and operating at a speed of seven strokes per minute, with the necessary air-vessel, all complete, to lift 6,000,000 gallons 200 feet high per day. The whole delivered, put up, and put in successful operation for $27,500. EMILE GEYELIN, Office Franklin Institute Hall, Philadelphia. Lieutenant M. C. MEIGS, U. S. Engineers, Washington, D. C. SMITHSONIAN INSTITUTION, DEAR SIR: Your note of yesterday was referred by Prof. Henry to me for answer. The preparation of the matter required some time and care, and was accidentally interrupted to-day, so as to prevent sending it at 12 o'clock. No reliable determination of the mean annual precipitation of the eastern slope of the Alleghanies, as a whole, has been made, nor has, as I am aware, been attempted. The materials are still very meagre, and perhaps inadequate for your purpose. But the same information has been sought from Baltimore and other places, and I have hastily grouped the records giving the means for the longest observed periods. The most important conclusion presented by the registers here is, that there is no local effect exhibited in any portion of the general plain east of the mountains from New York to South Carolina; nor is any decided change in the amount shown at stations on the mountains themselves. Philadelphia, Baltimore, Washington, and Richmond give very nearly the same amount for the year, and the same distribution among the months. This being the case, any local observations are unnecessary to fix the amount for this locality, or for any portion of the Potomac district. Most of those made here are interrupted or unreliable in some one or more months of the year. The amount of 40 or 41 inches will very nearly represent the mean annual fall, with extremes of 25 and 54 inches, and a very nearly equal mean distribution among the months. A fuller preparation of all existing records is being made for the whole country, which will more definitely establish the needed determinations in this much-neglected matter. Very respectfully, yours, LORIN BLODGET, In charge of meteorological reductions and report. Lieut. M. C. MEIGS. |