In 1870, Prof. Frederick Guthrie published an account of some interesting experiments "On Approach caused by Vibration," unaware at the time of the earlier labors of Dr. Guyot in the same direction. He found that a card suspended near a vibrating tuning-fork was urged toward the fork, and by varying the experiment with smoke, with cork, with calcined magnesia, with floss cotton, with a second suspended tuning-fork, with brass disks, etc., he obtained similar results. At the termination of his experiments he thus sums up: "The experimental results appear to me to point to the following conclusions : whenever an elastic medium is between two vibrating bodies, or between a vibrating body and one at rest, and when the vibrations are dispersed in consequence of their impact on one or both of the bodies, the bodies will be urged together. The dispersion of a vibration produces a similar effect to that produced by the dispersion of the air-current in Clement's experiment; and, like the latter, the effect is due to the pressure exerted by the medium, which is in a state of higher tension [or pressure] on the side of the body furthest from the origin of vibration than on the side toward it. In mechanics — in nature — there is no such thing as a pulling force. Though the term attraction may have been occasionally used in the above to denote the tendency of bodies to approach, the line of conclusions here indicated tends to argue that there is no such thing as attraction in the sense of a pulling force, and that two utterly isolated bodies cannot influence one another. If the aetherial vibrations which are supposed to constitute radiant heat resemble the serial vibrations which constitute sound, the heat which all bodies [272] possess, and which they are all supposed to radiate in exchange, will cause all bodies to be urged toward one another."[1]
This hypothesis would make gravitation, or molecular attraction, a function of temperature, contrary to all observation ; and is indeed entirely incompatible with the fourth, fifth, and sixth conditions of gravitative action. In short these experiments, striking and instructive as they unquestionably are, will be found on careful scrutiny to really simulate the effects of gravity in no one particular.
- ↑ L. E. D. Phil. Mag., November, 1870, vol. xl, p. 354.