656 TRANSACTIONS OP THE AMERICAN INSTITUTE. 



Dr. Vander Weyde read the following paper on 

 The Nebular theory of La Place. 



By general desire, I continue the subject of Cosmogony. Last 

 week I spoke on the nebuhir hypothesis of La Place as being ele- 

 vated into a theory by the new doctrine of the conservation of 

 forces. I have been requested to explain more in detail w^hat is 

 meant by this last expression: It means that never any force is 

 destroyed, that the apparent destruction of motion results usually 

 in raise of -temperature, which, by the modern improvements in 

 philosophical apparatus, may always be traced and measured. 

 You saw the delicate apparatus of Melloni, where the small amount 

 of heat produced by the destruction of the motion of a leaden 

 ball transformed into electricity, this electricity into magnetism, 

 and finally, this disturbing the compass needle, the slightest change 

 of temperature was made visible. The basis of the new doctrine 

 of the correlation of forces is, that like matter is indestructible ; 

 force is also indestmctible. Force is manifested by matter in 

 motion, which is chiefly visible when the masses are moving ; but 

 when the visible motion is apparently stopped, the mode of this 

 motion is only changed, it becomes molecular motion, vibration, 

 irritation of the atoms, and as such manifests itself as heat, elec- 

 tricity, magnetism, etc. (Here the Dr. explained how accoustics 

 had revealed many kinds of vibrations or waves of a nature differing 

 respectively in another way than in mere velocity or intensity; he 

 illustrated the character of those waves by diagrams on the black- 

 board. He explained how, after the manner of the sonorous wave, the 

 luminous and caloric waves differ in velocity, amplitude, direction, 

 etc., and gave a practical illustration of the polarization of light.) 



I stated that matter was diffused into space in a nebular state, 

 and came together by gravitation; and the most startling revela- 

 tion on this subject I communicated to you, was that different 

 kinds of elementary matter were not equally intermingled; that 

 the nebular matter was not homogeneous, as observations with the 

 spectroscope have proved at the present day; that the stars all 

 consist of different kinds of matter, and are distinct from one 

 another in their constituent elements, in the same way as diflerent 

 regions of our earth's surface contain differently distributed and 

 accumulated mineral substances. 



It is delightful to meditate in the light of modern chemistry 

 on the results of chemical action, when those diflerent elementary 



