V. VIBRATIONS AND WAVES. 125 



A. ramified tuning-fork. 



The same produces a sound composed of two tones, and marks the corre- 

 sponding musical note direct on a sooty glass plate. 



JB, resonator with monometrical flame without membrane. 



In a conical shaped Resonator, which is held with the large opening down- 

 wards, illuminating gas is filled from the top, which is allowed to escape through 

 an attached small tube and then ignited. The flame will react on the tones 

 (sounds) in the usual manner. 



C, an igneous Kaleidophon. 



Mr. Assistant Tollinger has shown that by fastening with wax a glimmering 

 candle to the end of a prismatic steel spring, a very commendable demon- 

 stration for large auditories can be produced of this well-known experiment. 



542 a. Apparatus for combining waves in one plane. The 

 resultant shown is that of two sets of waves (superposed) that 

 differ by half a wave-length. Chas. Brooke, F.R.S. 



542b. Apparatus for combining waves in two planes per- 

 pendicular to each other. The resultant shown is a right-handed 

 elliptic helix. Chas. Brooke, F.R.S. 



543. Stationary Liquid Wave Apparatus and Sector 

 Pendulum. Frederick Guthrie, F.R.S. 



When such a system of stationary waves is formed in a cylindrical deep 

 trough that the centre rises and falls as the edge falls or rises, the undu- 

 lation is synchronous with a pendulum whose length is equal to the radius of 

 the trough ; and the accelerations of motion of the wave and pendulum are 

 identical. 



544. Wheatstone's Wave Apparatus. A very complete 

 instrument, showing plane, circular, and elliptical waves, the 

 phenomena of interference, &c. Elliott Brothers. 



544a. Apparatus to illustrate Wave Motion. 



Rohrbeck and Luhme, Berlin. 



545. Illustrations of Vortex Motion. Nos. 1 and 2 are 



vibrations ; Nos. 3-5 steady motion. (Proceedings of Royal 

 Society of Edinburgh, 1 November 1875.) Sir William Thomson. 



Series of 1 1 successive figures of a simple vortex ring, performing violent 

 transverse vibrations of the first fundamental mode. 



No. 2. Series of 1 1 successive figures of a simple vortex ring performing 

 violent transverse vibrations of the second fundamental mode. 



Motion analogous to that of screw propellers backing the vortex cone, 

 being in each instance as it were the edge circumference of the screw 

 propeller. 



No. 3. Two-bladed screw. 



No. 4. Three-bladed screw. 



No. 5. Four-bladed screw. 



No. 6. Trefoil knot described in Sir W. Thomson's papers on vortex 

 motion. Transactions of Royal Society of Edinburgh for 1857 and 1858, and 

 figured on the back of the " Unseen Universe," by Professors P. G. Tait and 

 Balfour Stewart. 



