340 Mr. J.J. Waterston on the Heat engendered by the 
11 miles diameter, and allowing for the time, we find the 
sun’s annual loss of temperature to be 6°°125. This is asimple 
arithmetical deduction from the fact that the sun’s heat can melt 
about 2 feet of ice daily. The observations of Herschel and 
Forbes fix it at 1°835 foot (Phil. Trans. 1842); those of M. 
Pouillet at about one-third less (Taylor’s Scientific Memoirs, 
vol. iv.). If we assume 1°5 foot as the correct thickness, the 
yearly reduction of temperature is 4°59. If the specific heat of 
the matter of the sun corresponded with iron, this decrement of 
temperature would have to be multiplied by 9, and so on for 
other assumed values. But it is convenient to found our ideas 
of such quantitative relations on water as the standard most 
familiar. 
Assuming the earth to have six times the density of water, we 
may extend these calculations ; and comparing volumes and time, 
we deduce 69 as the number of years that the sun takes to throw 
out as much force as would accrue to it by the earth falling down 
upon its surface. The mechanical force thus supplied would be 
equivalent to the expenditure of heat-force for 69 years; and the 
rise of temperature of the whole mass of the sun, supposing the 
increment of heat uniformly diffused through its mass, would ap- 
proach as much nearer to the maximum limit 317° (=69 x 4°-59) 
as the temperature of the planet after impact exceeded the tem- 
perature of the sun. 
Again, if we suppose the planet after it has struck the surface 
of the sun to settle into a dise of 60,000 miles diameter, having 
the temperature of 100,000,000 degrees, the temperature of the 
sun being 12 millions, we should have 725th of its dise shining 
with eightfold lustre, giving out probably eight times as much 
8—1 1 
220 31 
represents the increment of solar heating power; and if we esti- 
mate the normal amount as what is required to keep the earth’s 
surface at a mean temperature of 60° F. or 521° absolute, we 
heat as an equal surface in the normal state. Thus 
521 : : 
see that ig 17° nearly, is the increment of mean temperature 
over all the earth that would arise from such a planet-fall. 
M. Pouillet infers from his observations on solar radiation, 
that the temperature of the sun’s surface is at least 2660° F. 
If it do not exceed this amount, the rise of temperature in the 
whole mass of the sun would be about 200°; but if, as before, 
we assume the planet to settle into a disc 2! in diameter, we 
have =},th of the sun’s dise shining with 38,000 times the normal 
force, so that a planet-fall of this magnitude would increase the 
radiating power of the sun 171 times. 
