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rotation and the age of the sun, he appears to have assumed, if I read 
him aright, that all the meteors in the solar neighbourhood are cir- 
culating in the same direction as the planets ; and it is extremely 
probable that this is true for the greater number of them. Indeed, 
the publication in France, since this paper was placed in the hands 
of your Secretary, of the apparent discovery of a planet interior to 
Mercury, at considerably less than half his heliocentric distance, 
and revolving direct , might be taken as a remarkable proof of the 
correctness of the assumption. Nevertheless, we cannot close our 
eyes to the fact, that the members of the solar system which occa- 
sionally come visibly closest to the sun are not planets, but comets, 
and that, amongst these, retrograde motion is frequent ; while of all 
comets, the one which has made the closest known approach, since 
the age of exact astronomy, was that of 1843, which was retrograde, 
and passed only 60,000 miles from the sun’s surface. Hence it is 
by no means an unwarranted supposition for us to make, that an 
occasional meteor moves retrograde also ; as, in fact, this one of 
September 1st appears to have done ; and if it should, in such a 
course, encounter another moving direct, in the crowded solar 
vicinity — a casualty that must become more and more probable 
with every advance towards the sun — there would be double speeds 
of motion to be converted into heat ; there would be much such a 
sudden blaze of light as the observers described ; and then a rapid 
descent of both bodies to the sun’s surface, through that remaining 
distance in which they might otherwise have long continued to cir- 
culate before their final absorption. 
On the whole, then, it appears exceedingly probable that the 
solar phenomenon of September 1st was a meteor falling to the 
sun, and giving out the heat of its mechanical energy in accordance 
with the laws of that dynamical theory of thermotics, first and 
chiefly in this country brought before the Poyal Society of Edin- 
burgh by Professors W. Thomson and Macquorn Pankine. In 
which case, there is another example added, to several that might be 
extracted from the history of science, showing that hardly has a 
true theory been published to the world, before a confirmatory 
phenomenon, previously quite unexpected, is almost providentially 
witnessed; and in no case by less prejudiced or more able observers 
than the gentlemen upon whom we depend in the present instance. 
