198 Prof. Norton on Molecular Physics. 



city and magnetism has yet been indicated by the advocates of 

 this theory. The electric fluid is expelled by them from the vast 

 field it has hitherto occupied, but all attempts to supply its place 

 have proved futile. 



2. Another obvious objection is, that vibratory motions of gross 

 atoms are supposed to originate the forces by which such atoms 

 are primarily aggregated into masses, whereas it is essential to 

 the possibility of such vibrations that contiguous atoms should 

 exercise a mutual action upon one another — that is, be previously 

 aggregated. We must suppose, then, the existence originally of 

 other forces, to bring isolated atoms together and make the sup- 

 posed forces due to vibratory motions of the atoms possible; 

 that is, these latter forces become possible only when there is no 

 longer any further occasion for them. We have seen that another 

 possible origin may be ascribed to such oscillatory waves that 

 does not involve the physical impossibility just referred to, from 

 which those who seek for the key to all molecular phenomena 

 in the motions of gross atoms can hardly escape. 



3. The notion advocated by Tyndall in his admirable work 

 on ' Heat considered as a Mode of Motion/ that heat and light 

 originate in a vibratory motion of ordinary atoms, involves the 

 supposition that these atoms are capable of vibrating at the 

 astonishing rate of six hundred trillion vibrations in a second, 

 while the most rapid vibration of atoms, or of a collection of 

 atoms, known to take place in the production of sound, does 

 not exceed 24,000 per second. It may be conjectured that this 

 immense chasm may be spanned by the idea that the ultimate 

 particles of bodies are immeasurably smaller than any collec- 

 tion of atoms which may be simultaneously vibrating when 

 bodies emit sound; and that since a musical string vibrates 

 more rapidly in proportion as it is shorter, a single particle may 

 vibrate at an inconceivably rapid rate by reason of its exceeding 

 minuteness. But the analogy here supposed does not exist as 

 a physical fact, and no such inference can be drawn from it ; for 

 the rate of vibration of the string depends upon the distance 

 between its two fixed points, but in no proper sense can it be 

 said that two particles between which another is situated, are 

 fixed, so as to be incapable of taking on the motion imparted to 

 the intermediate one. So far from this being the case, the dis- 

 placed particle can only vibrate by reason of the reaction of the 

 contiguous particles to the action which it exercises upon them ; 

 and in receiving this action the motion must be transmitted. If, 

 to remove the difficulty, we conceive the particle to oscillate as 

 if it were wholly isolated, in union with an oscillatory wave 

 falling upon it, we then fall upon the second objection stated 

 above, and seek in vain through the universe for the vibratory 



