260 
Now, this is fortunately easy of demonstration, for we have only to 
point to the red prominences, borders, and clouds, seen stretching to 
a distance of 60,000 miles sometimes from the edge of the solar orb 
during solar eclipses ; or to those unmistakable evidences of a large 
amount of outer absorbent and obstructing atmosphere, indicated by 
the gradual yellowing and de-photographical properties of the sun’s 
light, with every advance from the centre to the circumference of his 
disc. (See TenerifFe Report, “ Philosophical Transactions” for 1858, 
p, 487.) Something material, therefore, and forming to all intents 
and purposes one body with the sun, does exist round about him ; 
and capable, we cannot but allow, of affording impediment to the 
motion of any extraneous body, before it actually comes into contact 
with that intensely bright surface which is vulgarly held to consti- 
tute the outside of the sun. 
Hence, when we find our solar meteors of September 1 moving 
at a rate slower by 159 miles a second than they should do accord- 
ing to the laws of gravitation, the simplest assumption that we can 
make is, that there has been a mechanical retardation to that amount. 
Let this be granted, and then it necessarily follows from the dyna- 
mical theory of heat, that precisely in accordance with the disappear- 
ance of motion will be the appearance of heat. And when we fur- 
ther take account of the previous high temperature to which the 
matter of the meteor (for the two, we are inclined to look on as 
fragments of one ; unless Bielas’ double comet is to be taken as an 
argument for constant double meteors also) was brought, during the 
long ages of its circulation around the sun, in an orbit whose mean 
distance decreased only secularly ; and when we also consider the ex- 
traordinary warmth of the region where the observed rapid retarda- 
tion took place, it will be understood that everything was extremely 
favourable to the heat produced by conversion of motion, appearing 
with so intense an expression, as to be accompanied by a most vivid 
display of light. 
Even in the cold external atmosphere of the earth, and with a 
speed of only 19 miles in a second on the average to be converted, 
M. Joule has shown that meteors should become intensely white hot ; 
and Professor Swan has described in the “ Proceedings” of this So- 
ciety, Yol. III., p. 220, a case of one bright enough to be conspicu- 
ously seen at noonday. 
It is true that, according to Mr Waterston’s form of the theory, 
