456 TRANSACTIONS OF THE 



as a consequence, that when the nebulous matter aggregated heat was 

 evolved by the play of affinities, and by the mechanical compression of the 

 mass. When rotation ensued, fragments were driven off which became 

 planets round the centre sun ; thus all power may be traced first, to chem- 

 ical action, and secondly, to the sun. Professor Thompson considers that 

 the light and heat of the sun are maintained by the destruction of nebulous 

 or meteoric matter falling into it continually, and that still it loses one 

 minute of a degree of heat in 400,000 years. The sun is the great dis- 

 turber. If he were blotted out all nature would become quiescent. 



Profestor Hedrick. — The nebular hypothesis will give us no motion. 

 From some cause that we know nothing about, motion was obtained. In 

 the nebulous hypothesis, it is acknowledged that motion must have had 

 some cause, in order that matter might collect into masses and begin to re- 

 volve. Gravitation will not account for matter aggregating and com- 

 mencing to revolve in masses. 



Mr. Seeley protested against calling the sun a source of power. The sun 

 is not an ultimate source of power, but is only an accidental one. We 

 have got at no fact or well established theory, after a long evening's dis- 

 cussion, but have had simply the ideas of the speakers presented to us. 

 We speak of light, heat, and electricity, as matter that we can handle, yet 

 they are only peculiar conditions of matter, as sound is only air in motion. 

 Sound is conveyed to our senses at a moderate rate of speed, the undulations 

 which give the sensation of heat travel more rapidly, those of light still more 

 rapidly, while those which we call electricity travel the most rapidly of all. 

 In all these cases, though there is force expended to propagate the undula- 

 tions, no force is lost, for this effect is returned by the same medium, and 

 cause and effect are always equal and opposite. This may be illustrated by 

 a spring. We use force to compress a spring, but in expanding it will give 

 out the same amount, if perfectly clastic. In all cases of imponderable 

 agents, or forms of undulation, Mr. Grove thinks that they are convertible. 

 Light may be converted into heat or electricity, and vice versa. 



Mr. Tillman. — Vibrations in air give sound, and according to the undu- 

 latory hypothesis, their vibrations in ether give light. There are seven 

 distinct sounds or tones; there are also seven distinct kinds of light or 

 colors. The latter are found to be due to three distinct kinds of waves, 

 one of which produces the sensation of red, the other yellow, and the third 

 blue ; and these by their admixture in different proportions, give ail the 

 tints. By following the analogy between air and ether, sound and the im- 

 ponderable agents, we will find that light, heat, and electricity may all be 

 regarded as ether in vibration ; one form of vibration giving heat, another 

 light, and a third form giving electricity. 



The Chairman considered that the Association was now bordering upon 



discussions not suited to them. The term "cause" seems an irreverend 



idea, and the general consideration of ultimate causes as not pertinent to 



the objects for which the Association is established. ' 



On motion of Mr. Tillman, a committee of three was appointed to con- 



