Brexerton,—On Partial Impact, 181 
this hypothesis agrees with some of the spectroscopic observations of comets, 
in which the tail gave a feebly continuous spectrum, showing it to be solid, 
and the nucleus a banded spectrum, showing it to be gaseous. It may be 
possible that there are other gases whose temperature of decomposition is 
lower than the temperature of volatilization of one of their constituents, such 
as fluoride of silicon and generally halogen compounds of infusible bases. 
Lhe Sun. 
I shall now attempt to show that there may be agencies at work which 
may cause a great difference of temperature between the poles of the sun 
and its equator, This may give us an insight into the cause of the tremen- 
dous cyclones of the meeting solar trades, and these cyclones are possibly 
the cause of such spots. If this hypothesis really represents the formation 
of the solar system, then it is probable that radiation is greater in a direction 
perpendicular to the ecliptic than in its plane, Again, the combined energy 
of gravitation and centrifugal force would cause most of the absorbed matter 
to fall upon the sun about the equator; both of these causes may produce 
a great difference of temperature between the poles and the equator of the 
sun, sufficient, perhaps, to produce cyclonie spots. The projection of bodies 
upon the surface of the sun, bodies trapped by the sun itself, might probably 
produce the sea of flame which surrounds it, and the protuberances so often 
seen upon itslimbs. The precipitation of bodies upon its surface appears 
to me to offer the only conceivable explanation of the high velocity which 
the hydrogen on the surface of the sun sometimes possesses. The speed 
of some comets proves that bodies in space may have a velocity of many 
hundred miles per second, and we know that a body at rest would aequire 
nearly 400 miles a second by the sun's attraetion alone. Therefore many 
bodies may fall upon the sun with a velocity of 500 miles a second or more. 
Such a body would bury itself far down in the sun, clearing the gas by 
pressing it down before it and in a few minutes it would be many thousand 
miles into the sun, and, its motion of mass destroyed, a temperature of 
100,000,000 might readily be developed, which, even if the density of the 
body were no higher than air, would amount to a pressure of 400,000 
atmospheres, and would most likely be much greater than this. Here are 
all the conditions for a most powerful explosion, amply sufficient for all 
that has been observed of the prominences. It is quite evident that if there 
are trains of bodies, which have been brought into the orbits around the 
sun, most of the phenomena of periodical variations of spots and protuber- 
ances may be explained on the assumption that these bodies plunge 
obliquely into the body of the sun. 
On Double and Multiple Stars. 
When the original proper motion is small, and the proportions struck 
off large, after partial coalescence the greatly increased attraction acting on 
