CONTINUITY. 199 



duced their motions to a certain regularity in the motion of 

 the photosphere, attributable to some general action arising 

 from the internal mass of the sun. 



It might be expected that comets, bodies so light and so 

 easily deflected from their course, would show some symptoms 

 of being acted on by gravitation, were such a number of 

 bodies to exist in or near their paths as are pre-supposed in 

 this theory of solar heat. The sun may, however, meet sup- 

 plies of meteoric bodies and condense gaseous matter as it 

 travels in space (as the sun is now fairly proved to do), and so 

 heat may be produced. 



Assuming the undulatory theory of light to be true, and 

 that the motion which constitutes light is transmitted across 

 the interplanetary spaces by a highly elastic ether, then, unless 

 this motion is confined to one direction, unless there be no 

 interference, unless there be no viscosity, as it is now termed, 

 in the medium, and, consequently, no friction, light must lose 

 something in its progress from distant luminous bodies, that is 

 to say, must lose something as light ; for, as all reflecting 

 minds are now convinced that force cannot be annihilated, the 

 force is not lost, but its mode of action is changed. If light, 

 then, is lost as light (and the observations of Struve seem to 

 show this to be so, that in fact a star may be so far distant 

 that it can never be seen, in consequence of its luminous un- 

 dulations becoming extinct), what becomes of the transmitted 

 force lost as light, but existing in some other form ? So with 

 heat : our sun, our earth, and planets are constantly radiating 

 heat into space, so in all probability are the other suns, the 

 stars, and their attendant planets. What becomes of the heat 

 thus radiated into space ? If the universe have no limit and 

 it is difficult to conceive one heat and light should be every- 

 where uniform ; and night would be as light and as warm as 

 day. What becomes of the enormous force thus apparently 

 non-recurrent in the same form ? Does it return as palpable 

 motion ? Does it move or contribute to move suns and planets ? 

 Can it be conceived as a force similar to that which Newton 

 speculated on as universally repulsive and capable of being 

 substituted for universal attraction ? We are in no position 

 at present to answer such questions as these ; but I know of 



