garden." When lecturing in Glasgow, about 1875, the writer showed it
to his audience. The next morning, when removing his property from the
lecture table, he found that his precious relic had been stolen. It
would be interesting to know who has got it now!

[2] It must be noted that these words, in which the laws of
gravitation are always summarised in histories and text-books, do not
appear in the _Principia_; but, though they must have been composed by
some early commentator, it does not appear that their origin has been
traced. Nor does it appear that Newton ever extended the law beyond
the Solar System, and probably his caution would have led him to avoid
any statement of the kind until it should be proved.

With this exception the above statement of the law of universal
gravitation contains nothing that is not to be found in the
_Principia_; and the nearest approach to that statement occurs in the
Seventh Proposition of Book III.:--

Prop.: That gravitation occurs in all bodies, and that it is
proportional to the quantity of matter in each.

Cor. I.: The total attraction of gravitation on a planet arises, and
is composed, out of the attraction on the separate parts.

Cor. II.: The attraction on separate equal particles of a body is
reciprocally as the square of the distance from the particles.

[3] It is said that, when working out this final result, the
probability of its confirming that part of his theory which he had
reluctantly abandoned years before excited him so keenly that he was