Kindly keep your Queries on separate sheets of paper when corresponding about such matters as patents, subscriptions, books, etc. This will greatly facilitate answering your: questions, as in many cases they have to be referred to experts. The full name and address should 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. (12509) J. L. B. writes: You seem to imve an idea of heat waves which is not the orm accepted by physicists. See Maxwell s amp; apos; amp; bull; Tlieory of Heatamp; rdquo; (Longmans, Greenamp; amp; Co., 1904). On lower half of page 10 he defines three modes of heat transference. Then concerning one of these modes, on top page 237, he says : amp; ldquo; Hence all that we have said about the waves of light is applicable to heat radiation, which is therefore a series of waves.amp; rdquo; Rearranging the sentence, we gut that a series of heat waves is therefore heat radiation. Then see Preston, amp; ldquo; Theory of Heatamp; rdquo; (1904), page 56, top paragraph, where he states that all matter at any temperature gives waves of heat. Follow this with page 519 at bottom; amp; ldquo; We shall confine our attention to the process of radiation, which does not appear to depend in anyway on t hp pves enee of matter, but which takes place through the best vacua, and through interstellar spaces.amp; rdquo; This substantiates my original statement that a vacuum is no insulator for heat (raves, i. e., radiation. Conduction and convection are eimiminated as modes of heat transference by surrounding a body with a vacuum, and the radiation is made as small as possible by using a polished surface. See Preston, page 520, article 259, on the radiation of polished surfaces. In regard to the second part of my criticism, let me cite amp; ldquo; Modern Electrical Theory,amp; rdquo; Campbell (Cambridge Series, 1907), page 106: amp; ldquo; And the mean kinetic energy of the molecules in virtue of their speed of agi-ta tion is proportional to the temperature of the gas on the absolute scale.amp; rdquo; Also amp; ldquo; Kinetic Theory,amp; rdquo; by Boynton (Macmillan Compan y, 1D04), page 42 : amp; ldquo; Two gases are at the same temperature when their molecules have the same mean kinetic energy.amp; rdquo; In neither case is any reference made to the number of collisions as having any necessary connection with the temperature. In Maxwell ("Theory of lleat"), page :12. we find the equation: v velocity. 1) amp; equals; volume. p amp; equals; pressure. And also the statement that pv and 1amp; sol; 2 1)2 are proportional to absolute temperature. No term showing number of collisions of molecules is given. The number of collisions per second is given by .an equation in Boynton, page 57 : 1 nac T V n amp; equals; number of molecules per c. c. 8 amp; mdash; m2 in cross section of molecule. c amp; equals; velocity of molecule. V amp; equals; total volume considered. T amp; equals; time between collisions. 1 amp; mdash; amp; equals; number of collisions per second. T Notice that the velocity is only one of four factors that determine the number of collisions per second, so that the temperature of a gas and velocity of its molecules may be increased without increasing the number of collisions, provided the other factors (for example 21) be changed in the proper ratio. This substantiates my original statement that the number of collisions is not a necessary cause or result of a rise in temperature of a gas. (12510) C. E. A. asks: Wishing to make a funnel froin sheet iron, is there any Way to lay it out, with say 0-inch top and 2-i neli base? A. It is very easy to lay out a funnel, thus : Draw a side view of the funnel, full size. produce the side lines to meet at a point, draw two circles from this point as a center and step off on either of the circles, with a pair of dividers set to a small space, a distance equal to the circumference of the funnel; then cut out the pattern.
This article was originally published with the title "Notes and Queries" in Scientific American 105, 6, 128 (August 1911)