228 Scientific Intelligence. 
Professor Heckel may make any assumption he chooses about 
the age of the sun, but he must not do so in regard to the age of 
the sun’s heat. One who believes it inconceivable that matter can 
either be created or annihilated may be allowed to maintain that 
the sun existed from all eternity, but he cannot be permitted to 
her source, in addition, at least, to 
in a heated condition then in condensing it would have to part 
not merely with the heat of condensation, but also with the heat 
it originally possessed. 
The question then arises—By what means could the nebulous 
mass have become incandescent? From what source could the 
heat have been obtained? The dynamical theory of heat affords, 
as was shown several years ago (Phil. Mag. for May, 1868), an 
easy answer to this question. The answer is that the energy 1n 
the form of heat » y the mass may have been derived 
from motion in space. i 
les per second, would, by their concussion, generate In a single 
moving with a velocity of 476 miles per second, would possess 
4,149 10” foot-pounds of kinetic ener. , and this, converted into 
heat by the stoppage of their motion, would give out an amount 
of heat which would cover the present rate of the sun’s radiation 
for a period of 50,000,000 years, 
There is nothing very extraordinary in the velocity which we 
have found would be required to generate the 50,000,000 years’ 
heat in the case of the two Supposed bodies. A comet having an 
orbit extending to the path of the planet Neptune, approaching 
Ss 
5 Saar 
