(14) A. H. B. asks how much weight, falling 10 feet, will be required to produce one horse power for five hours? A. One horse power for 5 hours = 33,000 × 300 = 9,900,000 foot pounds—so that the weight required is 9,900,000 ÷ 10 = 990,000 lbs.
(15) A. D. R. asks: 1. In renewing a Leclanche battery, do the zincs have to be amalgamated? A. They are usually amalgamated. 2. Will two cells large size Leclanche battery give any light, using the simple lamp described in Supplement No. 162? A. No.
(16) H. L. J. writes: In a recent issue of the Scientific American you state that the floating of solid iron on melted iron is on the same principle as the floating of ice in water. I do not quite understand how it can be. Please explain. A. Solid iron, at an elevated temperature, floats upon molten iron for the same reason that ice floats upon molten ice-water—because it is specifically lighter. You will find the subject discussed at length in Tyndall's "Heat as a Mode of Motion."
(17) J. W. will find full directions for canning corn, etc., on p. 394 (4), vol. 39, Scientific American.
(18) "Amateur" writes: I wish to make some small bells that have a clear ring. What metal or metals can I use that I can melt easily? A. Use an alloy of tin and antimony. See Scientific American Supplement No. 17.
(19) H.—A nutritious mixed diet is unquestionably the best, care being taken to avoid an excess of meat.
(20) W. F. writes: I have made an engine, and would like to find out what size of boiler it will require. The cylinder has 2¼ inch bore and 3 inches stroke. A. It depends upon pressure and speed to be maintained; probably a vertical tubular boiler, 15 inches diameter, and 32 to 36 inches high, would suit you.
(21) R. G. (Salt Lake).—Please send full name.
(22) J. M. G. asks: If two persons each pull one hundred pounds on opposite ends of a rope, what will be the strain on the rope? A. The strain on the rope will be 100 lbs.
(23) W. M. M. asks: In laying off a mill stone in furrows, what draught is given? What amount of the space of a stone is given to furrows and what to grinding surface? A. There is considerable difference in the practice of various millers, and we would be glad to receive communications from those experienced in the art of dressing millstones.