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Kindly keep your queries on separate sheets of paper when corresponding about such matteFs as patents, su!scriptions, books, etc. This wlII greatly faclhtate answering your questions, as in many cases they have to be referred to experts. The full name and address SllOUld be given on every sheet. No attention will be paid to unsigned queries. Full hints to correspondents are printed from time to time and will be mailed on request. (12529) F. L. R. asks: What makes a horse hair when placed in stiII water wiggle like a snake? When one holds a hair of a horse in tbe hand it doesn't move a particle, but placing it in water starts the movement. What I would like to know is : what furnishes the power for the movement? A. Any motion a horse hair may have when put into water is caused by its power to absorb water and to bend or twist as the water causes the hair to swell on one side mOTe than on another. This will take place in the air. If you hang a long hair by one end and , tie to the lower end a light rod of wood or a piece of straw perhaps six inches long, you will find that it will twist back and fprth from day to day. (12530) C. T. C. asks. In an air pump that drawn out 2 Inches makes a practical vacuum, the outside air pressure is said to be 15 pounds to the square inch. Now suppose the piston to be drawn out to 4 inche” and 6 I!ches and 8 inches, is the air pressure on the piston any more at 8 inches than it is at 2 inches? A. If there is no space whatever between the piston and cylinder head—no “clearance"-there will be a perfect vacuum (theoreticaIIy) behind the piston the instant after It comimences to move, and an unbalanced pressure of 14.7 pounds per square inch on the opposite face of the piston, and. this pressure wiII not increase as the piston is drawn out. In fact, the atmospheric pressure may be considered constant, while the pressure behind the piston, equal to atmospheric at first, drops instantly as the piston begins to move. (12531) H. L. W. says: Can you lower the temperature of ice below 32 deg. F. ; if so, what ratio does the lowering the temperature of the surroundings berur with the temperature of the ice? A. Ice, like any other solid, takes the temperature of the place in which it is, when thRt temperature is below its melting point. In a cold region when the temperature is at zero, a block of ice will cool to zero, just a:s the stones do and as m pidfy according to some experiments, while others seem to show that it will cool less rapidly than tne stones. Waterr, as a solid, has the properties of other solids. Its melting point is low as compared with most soLids, and for that reRson, we suppose, people do not usually associate it with solids. (12532) H. C. says: 1. I read somewhere, some years ago, that the moon possessed a small satellUe, some few miles in diameter, occasionally visible. I have seen no other reference to it and cannot now place the reminiscence. Is this a fact? A. 1. No satellite of the moon Is known to exist. There ;s no mention of such a body in the astronomies. 2. Why do the ether,lc waves used In wireless telegraphy bend round the earth? Why do they not take theirr way through the ether altogether irrespective of material bodies ? A. 2. The antenna of a wireless telegraph apparatus is equivalent to one-half of a Hertztan oscillator, the other half of which is the earth. A complete Hertzian osclIIa:tor does give 00 waves which go through space like light waves iudependent of the earth. A gl'ounded oscillator gives jff half waves, the lower part of which are not closed lines, but terminate in the earth, and cannot sepaTate from it. They therefore follow the contour
