﻿Dr. Guyot on the Forms and Forces of Matter. 417 



opposite to the centres of oscillation, as experiment proves. 

 But experiment also shows that no such attraction takes place 

 opposite the nodes. There is therefore nothing in common be- 

 tween the attractions of the segments of vibration and the nodal 

 lines traced out by light powders on plates, or exhibited by little 

 paper saddles on a stretched cord. Electricity also has nothing 

 whatever to do with these attractions, because they occur in me- 

 tallic vibrating bodies as well as in those of glass, in water as in 

 air. MM. Dulong and Savart, with whom I have repeated my 

 experiments, have, moreover, conclusively shown that neither 

 nodes of vibration nor electricity play any part in these attrac- 

 tions by sonorous vibrations. 



In order better to fix the minds of my readers upon the true 

 action of solid vibrating bodies on the elastic fluids which touch 

 them, I pour some water into a bell-glass on a stem, and by 

 means of the bow I extract the lowest sound which it can pro- 

 duce, one sees distinctly four segments in vibration, and four 

 nodes which divide the liquid circle into four quarters. 



If the bow be drawn gently along the edge of the vase without 

 the slightest deviation, the segments of vibration appear formed 

 of rays perpendicular to the surface of the glass, and which are 

 longer accordingly as they are nearer to the centre of this seg- 

 ment. They are also of a length proportional to the intensity 

 of the vibration. If the bow varies in position, the rays cross 

 in all directions like the hatching of a drawing. If the vibra- 

 tion reach its maximum, the water is powdered and hovers in 

 the form of a mist above the liquid. If the bell sounds the 

 higher octave, there are eight segments of vibration, smaller, 

 but presenting the same phenomena of radiation and projection 

 of the water. In both cases the water remains at rest at the nodes 

 and in the centre of the vase. 



This experiment proves that the vibrations of solid bodies 

 strike and forcibly disperse the elastic media in which they are 

 plunged, that they rarefy these media in their sphere of action, 

 and diminish their pressure more and more according to the 

 proximity to their surfaces. 



In order to show this fact still better, I hang a gold coin 

 from two threads so that it cannot turn on its axis. I plunge 

 it into the water opposite to a segment of vibration, at a 

 distance of one or two centimetres from the interior surface of 

 the vase, and on setting the vase in vibration by the bow, the 

 coin is brought into contact with the glass. If the coin be op- 

 posite to a node it is not attracted. 



I shall return later to these experiments, which I shall 

 complete by showing that vibrating cords attract at one end and 

 repel at the other, that a strip of paper hung in a bell always 

 adjusts itself between two segments of vibration. Any one can 



