491 
of Edinburgh, Session 1877 - 78 . 
of the numerical amounts of the perturbations it is subject to from 
other planets. His third paper, presented in 1844, investigated in 
the most masterly style the perturbations which the strangely 
deflected Comet of 1770 must have experienced both before and 
after that epoch, from the attraction of the planet Jupiter. And 
his fourth paper, applied similar mathematical calculations to the 
more modern discovered Comet of 1843. 
But those Comet papers, though they gained Le Yerrier a seat 
and a pension in the Academy of Sciences, were not altogether in 
his destined line. In more immediate resumption of which, it was, 
that in the beginning of 1846, he brought before the Academy his 
fine investigation into the orbit of the planet Uranus, his computa- 
tions of every perturbation it could suffer from every known mem- 
ber of the solar system, and his finding them all insufficient to 
account for the difference between theory and observation. And 
then, after that essential clearing of the ground, he produced his 
further and most remarkable of all his mathematical calculations, 
confessedly and by its very title, on “ the hitherto unseen, outside 
planet, which, acting from without, is producing the apparent 
irregularities in the movement of Uranus, from a distance of 1500 
millions of miles beyond, and is now in such and such a position in 
our sky, and must have such and such an apparent diameter.” A note 
of that position and size Le Yerrier sent to a German observer 
on the 17th of September in that year, 1846. That observer, Dr 
Galie by name, looked for it on the evening of the 23d of that 
month, and within a few minutes, with the powerful and accurately 
mounted equatorial telescope of the Berlin Observatory, he actually 
succeeded in finding Le Yerrier’s theoretical planet, since called 
Neptune, in the given direction, at the enormous distance and of 
the indicated size, nearly. 
This was the discovery, sensational it has been called, but most 
worthy to make a sensation throughout the whole human race, 
which immediately brought in honours of every kind, and from many 
nations to Le Yerrier. Which presently too, wafted him in political 
safety across the abyss which proved fatal to the then king and all 
the royal family of France ; but gave the astronomer-mathematician 
an eminent place under the subsequent republic, and a still more 
eminent one under the Empire which followed. But none of those 
