60 



HABIT AND INTELLIGENCE. 



[chap. 



Motions 

 of the 

 suu's at- 

 mosphere. 



Solar 

 spots. 



Combus- 

 tion an in- 

 sufficient 

 source. 



If these small planets move round the sun, it cannot be 

 doubted that, like the larger planets, they move from west 

 to east. Mr. Carrington's meteor, as already mentioned, 

 moved in that direction. If, now, meteors are constantly 

 falling into the sun's atmosphere, moving from west to east 

 with the velocity of a planet at the sun's surface, and in 

 greatest number nearest the equator, there is a motive 

 power which may be expected to drive the atmosphere 

 round the sun in the same direction, and with greatest 

 velocity at the equator. Mr. Carrington's observations on 

 the motion of the solar spots appear to show that such is 

 the case. The solid globe of the sun is concealed by 

 clouds, but Mr. Carrington has ascertained that the spots 

 which are formed among the clouds of his atmosphere move 

 most rapidly from west to east in the lowest latitudes, 

 showing the relative directions of the atmospheric currents 

 to be what the meteoric theory requires. If on the con- 

 trary the sun's atmosphere, like the earth's, were acted on 

 by no other motive power than unequal heating at different 

 latitudes, the relative direction of the currents would be 

 the reverse of this, in virtue of the well-known principle 

 of the trade-winds and "counter-trades," and this would 

 be true at all depths in his atmosphere. 



The meteoric theory does not, so far as I can see, throw 

 any light on the difficult question of the nature of the 

 solar spots, but it suggests a reason why they should be 

 formed where they are. They are formed only in the lower 

 latitudes of the sun, where, as already remarked, the greatest 

 number of meteors probably fall in, and where consequently 

 there must be the most atmospheric disturbance. 



If the sun is still receiving supplies of energy for con- 

 version into heat, and is not merely expending an original 

 stock, the falling in of meteors is the only possible mode 

 of such supply. The most obvious notion is that solar 

 heat is heat of combustion. But combustion is altogether 

 an inadequate source. We have seen that the energy 

 of motion with which a meteor will fall to the surface of 

 the sun is equivalent to a greater quantity of heat than 

 that which would be produced by the combustion of four 



