lxiv 



each wave, without being borne in upon the beach. This shows that the 

 waves are only the undulating motions of the fluid and do not indicate 

 the existence of a current in the fluid itself. 



According as the ethereal waves break more or less rapidly on the re- 

 tina, the various sensations of color are created. The waves more rapid 

 than the red create the impression of orange; those still more rapid, of 

 yellow; and as they increase in rapidity, the sense of green, blue, indigo 

 and violet are created; the violet rays being the most rapid of all that 

 affect the retina. Thus color is to the eye what pitch in music is to the 

 ear. Hence color may justly be termed the music of the spheres. The 

 red corresponds with the low musical notes and the violet with the higher 

 ones. 



The ear, though less sensitive, is, however, far more comprehensive 

 in its range than the eye, the eye being limited to a single octave of wave- 

 lets, whilst the ear embraces eleven. Each octave is produced by double 

 the number of waves of the octave below it. 



The ultimate particles of matter do not seem to be so closely com- 

 pacted, even in the densest metals, as to prevent a freedom of movement 

 among themselves to such an extent as to admit of a vibratory or mole- 

 cular motion. This motion reveals itself to us by the sense of heat. Heat 

 is simply molecular motion. 



If we imagine an atom of matter surrounded by other atoms, yet not 

 so closely as to prevent a certain degree of movement, and the first atom 

 have motion imparted to it, it will, if perfectly elastic, rebound when it 

 has reached the limit of its motion in one direction, and then, if it were 

 not retarded by friction, the luminiferous ether, or some other influence, 

 it would rebound with undiminished force in the opposite direction, and 

 thus repeat its vibrations forever. 



A tuning-fork makes a definite number of vibrations in a given time, 

 whether the vibrations be of great or small amplitude, and we have good 

 reason to believe that the vibratory swing of an atom of matter always 

 requires a certain period of time also for its movement, whether the ex- 

 tent of vibration be great or small. This amplitude of vibration may vary 

 very greatly however. When the hand is laid on iron, if the amplitude 

 of the vibrations be small, the piece will appear cold. If the amplitude be 

 great, it will appear hot, and it will then impart to the ether in contact 

 with it, and to the atoms of the hand, a motion corresponding with its 

 own periods of vibration. This vibratory motion of the atoms, or mole- 

 cules of matter, is revealed to us by the sense of heat, either by direct 

 contact with the substance, or by the impinging upon our bodies of the 

 ethereal waves which are set in motion by the heated body. Therefore, 

 when we approach an object whose atoms are in more violent vibration 

 than our own, we experience an increased sense of warmth, caused by (he 

 atoms of our body having an increased degree of motion imparted to them 

 from the increased amplitude of the vibrations of the ether. 



When the amplitude of the vibrations become so excessive as to over- 

 come the attractive force by which the atoms are held together in the 



