MR. HERMANN SMITH, in a letter in NATURE last week, commenting upon my paper read before the Physical Society on June 10, of which you gave a short report, offers some very cogent experiments in support of the evidence I have endeavoured to give, that the tuning-fork does not communicate its sonorous vibrations to a sounding-board through a ventroid, as we find generally accepted upon the theory of Chladni. In remarks upon my paper at the Physical Society, Lord Rayleigh suggested that this matter could be demonstrated by cutting a tuning-fork out in both ends of a long steel bar in the manner I had done, for an experiment, in one end only; we might then observe if sonorous vibrations would be communicated through either of the prongs of the double fork, at the opposite end to that set in vibration. In the following week I constructed such a fork, and I found that either of the non-vibrating prongs, when the opposite ones were set in vibration, would form a perfect stem to the fork, and communicate sonorous vibrations just as well as a single stem. In this case it will be seen that the prongs, which may be considered to form the stem, lead directly to the places on the fork pointed out as its nodes by Chladni. It appears, therefore, evident that a node may communicate sonorous vibration to a sounding-board.