EXPENDITURE AND SUPPLY. 23 



for the sun's wants. If every year the sun devoured a 

 quantity of meteors whose collective mass would form a 

 globe equal to our moon, then the quantity of meteoric 

 matter roaming about our system must be enormously 

 greater than seems likely to be the case. Indeed, it can 

 be shown that if so mighty a mass of material is absorbed 

 into the sun in the course of twelve months, the dynamical 

 conditions of the solar system would be widely different 

 from what we find them. A quantity of matter so distri- 

 buted that the sun could daily abstract a supply sufficient 

 for its wants would undoubtedly affect the movements of 

 the other heavenly bodies. Were there such an abundance 

 of substance in the vicinity of the sun, the perturbations 

 of Mercury and of the other planets arising from this 

 cause would be assuredly appreciable. As we do not find 

 that the movements of the planets are so affected to the 

 necessary extent, it is incumbent on us to conclude that 

 the quantity of loose material in our system cannot be 

 nearly so great as this doctrine of sun heat would require. 

 We are hence forced to take a modified view of the capa- 

 city of meteors to supply the solar radiation. It may 

 possibly be true, nay, doubtless must be true, that the 

 meteors do contribute, to some small extent, to neutralize 

 the sun's perennial losses ; but it is wholly impossible that 

 they can contribute in any substantial degree to the solu- 

 tion of the problem as to how the loss of heat by the sun 

 does not become apparent. 



Three suggested sources for the sun's heat have been 

 tested and found wanting. We have first considered it as 

 a mere glowing globe, gradually cooling and dispensing 

 its heat by radiation. This will not answer, for the sun 



