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Cement Drain Tiles Wanted. To the Editor of the Scientific American: I see by an advertisement in your paper that it is now possible to make good building blocks of sand and cement at a cost of six cents each--blocks worth eighteen cents each for use in building a house wall. This leads me to suggest that some one of the makers of machines for this purpose might do well for himself and others by inventing a machine for turning out tiles for farm drainage. Good burnt-clay tiles three inches in diameter cost from ten to twelve dollars per thousand at the factory, but by the time they reach the back-country farmer the cost runs up to twenty-five dollars and often much more. I should suppose that a farmer who has sand at home could make cement tiles at a cost far below that, provided he had the right apparatus. Of course, such a machine must be, first of all, simple, and to this end I venture to suggest that a tile with the cross section of the letter U might be easier to make than the tube tile. In fact, I have seen the . Indians in Central America making roof tiles of that shape by laying the clay half way round a tree trunk of the right size. Better still, I think, might be flat tiles having one edge notched, so that when laid together like the sides of an A roof, they would dovetail together. If well designed, such a line of tiles would never get out of place, and it would drain the land in half the time required by the tube tiles. John R. Spears. Northwood, N. Y., January 16, 1906 The Heat of the Subway. To the Editor of the Scientific American: I would judge from the different articles that I have read that the excessive heat of the Subway is somewhat of a mystery, and in your last issue of the Scientific American you state that a large amount of it is probably due to the powerful action of the West-inghouse brakes. This I will admit is true as far as that goes; however, I will ask this question: Is it not true that all of the electrical energy fed into the Subway is finally converted into ' heat in one way or another? I claim that it makes no difference whether the electrical energy is all used in heaters or in motors, the heat units of the current in both cases are exactly the same. If we use this electrical force through electric heaters; the conversion into heat is direct; if we use it to run motors, about 15 per cent goes into heat direct by losses in the motors, and the other 85 per cent goes into mechanical energy or power, which is again converted into heat by the friction of bearings, the brakes, and the wind resistance of the trains. There is no way to fool this natural law, and to make the motors act as generators will give the same amount of heat as the brake shoes for stopping the trains, unless such generators could be used for charging storage batteries, which afterward could be discharged outside of the Subway. Ventilation or cold storage pipes is the only remedy. E. A. Barber, Superintendent Black River Traction Company. Watertown, N. Y., December 30, 1905. The Consequences of Water Diversion from the Croton Valley. To the Editor of the Scientific American: The processes of water gathering and sanitary protection of streams in the Croton valley have been going on since 1842, when the first gravity supply was introduced into New York. If these processes have any effect upon the development of a drainage area, whether beneficial or otherwise, this periied {f sixty years is long enough to afford trustworthy results of what takes place. Such results are not only interesting in pointing out the destiny of this particular valley, but are of importance as an indication of what will take place in other regions under similar conditions. The Croton watershed of 360 square miles is wholly within the counties of Westchester, Putnam, and Dutchess. The townships which include the watershed are thirteen in number and are 413 square miles in area, so that the area affected by the water gathering constitutes 8T per cent of the area of the townships. The following table shows the population of all the townships in ten-year periods from 1850 to 1900, according to the census returns: Year. Population. 1850 ................................. 24,323 1860 ................................ 26,068 1870 ................................. 26,408 1880 ................................. 27,406 1890 ................................. 26,405 1900 ................................. 23,576 The gain in -these townships for the ten years ended 1860 was 18 per cent; for the twenty years to 1870, 14 per cent; for the thirty years to 1880, 12 per cent; for the forty years to 1890, 7 per cent; for the fifty years to 1900, the loss was 3 per cent. During this same period of fifty years the State has increased in population 125 per cent; the county of New York, 300 per cent; the three combined counties in which the Croton basin is located, 113 per cent. The density of population of the townships comprising the Croton basin was 59 to the square mile in 1850, and 57 in 1900. In the combined counties of Westchester, Putnam, and Dutchess the density was 84 in 1850 and 179 in 1900. The influence for retardation exhibited in the above census figures is remarkable for its persistence, inasmuch as the area affected possessed many features favorable for a normal growth. It contained thirty-one natural lakes and much beauty of scenery to attract residents. ' As early as 1852 the Harlem Railroad brought the entire length of the watershed into close connection with New York city.' Without the presence of the water gatherer it stood in a good position to sympathize in development with the city, which has always had a record of doubling every seventeen years. That there has been a positive influence against the progress of the townships comprising the Croton watershed is now made manifest and it may be recorded as an indisputable fact that the sanitary control and partial appropriation of land by the city for the purpose of diverting the maximum yield of water has in this instance resulted in retardation. The question now to be answered by those interested in the welfare of the State is this : Will these same consequences follow the diversion of 500,000,000 gallons daily from the streams in the Catskill region? and, if so, whether or not the devotion in perpetuity of 900 square miles of drainage afea is justifiable in the face of the fact that an equivalent supply may be obtained without resorting to the process of diversion at all, namely, by conserving the rainfall at the sources of the Hudson River for the twofold purpose of flood protection and the generation of electric power, the latter to be transmitted by wire to a station near Poughkeepsie and there utilized to pump the river water through an aqueduct to New York. Under this project the expenditure by the city does not injure the inhabitants of any extent of country, but o1 the contrary equalizes the fiow of streams and aids in industrial development. The estimated cost of the Catskill gravity project is 161,000,000, and the estimated, cost of the Hudson River pumping project is 108,000,000, showing a difference of 30 per cent in favor of the latter. This wide difference is due to the fact that the required storage in the Catskill region' will cost over 50,000,000, while the required storage on the upper Hudson will not cost 3,000,000. It would be utterly impossible to spend 50,000,000 in providing storage for a daily supply of 500,000,000 gallons anywhere in the State except in the Catskill Mountains. The topography of the country explains that fact fully, but the following quotation from the report of Mr. G. W. Rafter, C. E., to the Water Storage Commission points out how favorable in comparison is the topography of some other watersheds for storage. These several reservoir systems (Hudson, Genesee, Salmon, and Black rivers) have a total capacity of 139,000 million cubic feet, an amount of water sufficient, if uniformly distributed, to produce continuously, under the existing conditions of fall on the various streams, about 4,00,000 horse-power, worth at 12 per year per horse-power, 4,800,000. But 4,800,000 is the interest on 120,000,000; hence this amount of money could be actually invested in combined fiood protection and water storage for power purposes before the project would become commercially impracticable. As a matter of fact, the storage system here outlined will not exceed in cost 17,000,000. The average cost for storage for each horse-power in these four river systems is accordingly 42.50, and at this rate the 55,000 horse-power necessary to pump 500,000,000 gallons of water daily from the river to an elevation of 400 feet can be provided in the upper Hudson watershed by the expenditure of 2,237,500. By the generation of electric power at the source of the Hudson and the utilization of this power down stream one hundred miles or more an economy will be brought about that will save the city more than forty million dollars and save the State from sacrificing to the water gatherer what properly belongs to the tax gatherer. R. D. A. Parrott. 100 East 17th Street, New York, January 22, 1906.
