188 Mr Joseph John Murphy on the CirculaUo7i 



its axis, and is hotter at the equator than at the poles, the 

 system of atmospheric circulation must be essentially the 

 same as that of the earth. 



The sun is such a planet. Its rotation has long been 

 known, and Secchi of Eome has ascertained that its equa- 

 torial regions are sensibly hotter than the polar. No cause, 

 I believe, has hitherto been assigned for this difference. 



Mayer, Mr Waterston, and Professor William Thomson, 

 have brought forward very strong reasons for believing that 

 the sun is receiving a constant supply of heat by the fall of 

 meteors from external space into his atmosphere ; and Mr 

 Carrington and another observer have simultaneously ob- 

 served two meteor-like bodies of intense brightness sud- 

 denly appear on the sun's disc, and rapidly move across it 

 from west to east. If, as is all but certain, meteors' are 

 small planet -like bodies, it can scarcely be doubted that the 

 meteors, which supply the sun with heat, move round the 

 sun from west to east like the entire solar system, and, like 

 it, exist in a space of the form of a very oblate spheroid, 

 having its greatest diameter nearly in the plane of the sun's 

 equator. Consequently, the largest proportion of meteors 

 must fall on the sun's equatorial regions, making them 

 hotter than the poles. 



It can scarcely be doubted that the meteors must enter 

 the sun's atmosphere with a tangential velocity not much 

 short of that of a planet revolving at that distance. We 

 know^ that the sun's rotatory motion is incomparably less 

 than this, and, consequently, the meteors, moving from 

 west to east, ought to make the sun's atmosphere move 

 round his body in the same direction, and with greatest 

 velocity in the equatorial regions, as most meteors will fall 

 in there. At the same time, the difference of temperature 

 between the sun's equator and his poles, combined with his 

 rotation on his axis, will tend to produce a system of cir- 

 culation similar to that of the earth's atmosphere, and the 

 actual circulation will be the resultant of this and of the 

 motion from west to east, produced by the infalling meteors. 

 Mr Carrington's comparison of the motions of the solar spots 

 at different latitudes,* affords proof that such a circulation 



Proceedings of tlie Royal Astronomical Society, 13th April 1860. Mr 



