232 Original Articles. [April, 
52° 49' hel. lat.: that is to say, almost exactly at the latitude where 
the spots cease to afford us any further information. Its velocity 
estimated as a surface current at this latitude would be 357 miles per 
hour. 
There is a considerable analogy in such a system of movements to 
our N.E. and §.E. trade-winds. These also are nal in intensity on the 
equator, and increase in strength with the latitude, up to a certain 
maximum. ‘This, it is true, occurs in a considerably lower latitude than 
538°, but in our ignorance of the law of distribution of temperature over 
the sun’s surface, this can hardly be considered a fatal objection, 
especially when coupled with the very moderate velocity (for such a 
globe as the sun) assigned as their maximum. ‘To render it ap- 
plicable, the photosphere (within the maculiferous region) must be 
assumed to float, and be entirely contained in the indraft current (that 
which sets towards the sun’s equator), and this must also be (within 
that region) the wpper current, to provide for the carrying back into 
the circulation and redistribution of its matter (perhaps in a less 
luminous state) over the general surface, by the lower: constituting 
possibly the lower envelope which forms the penumbra of a spot; the 
spot itself, both umbra and penumbra, being a region in which, owing 
to some cause of disturbance, the movement of the lower current is 
arrested, and thrown into eddies and ripples. In this view of things, 
the temperature of the equatorial atmosphere must be supposed 
generally lower than that of the polar, which is not incompatible with, 
but on the contrary may be caused by, a more copious emission of heat 
from the former region, which, as Professor Secchi assures us, is really 
the case. 
II. On the second of our two extreme hypotheses, that which makes 
the globe of the sun revolve in 30%:86, the conclusion is very ob- 
vious. As the solar atmosphere must then in its entirety revolve 
quicker than the enclosed globe. there must prevail at every point of 
the surface of the latter a steady and uniform West wind, increasing 
regularly in intensity from nil at the poles, up to 880 miles per hour 
at the equator. As this current must continually tend to accelerate 
the rotation of the globe by friction, which by the law of reaction must 
tend to induce a state of relative quiescence, while yet the exterior 
current is maintained unabated—-this can only be by a force ab extra, 
and we have nothing to fall back upon for such a force but the friction 
of external matter circulating round the sun according to the laws of 
planetary motion, and that of the zodiacal light (the plane of whose 
greatest extension according to the best account we have of it, coin- 
cides with the sun’s equator) is ready at hand. In that case between 
a rotation in 25 days, that of the photosphere, and 3 hours that of 
planetary matter revolving freely at 1-10th of the sun’s radius above its 
surface, 7. e. between a velocity of 4,609 miles per hour in the former, 
and 1,012,000 in the latter case, every intermediate gradation of 
velocity must subsist, while between the photosphere and the globe a 
difference of velocity of only 880 miles per hour exists. 
However enormous this velocity of the external matter, and what- 
ever the density we may attribute to it, we have to accept this last- 
