globe, and there can be no doubt that they are gradually reducing its
speed, and thus lengthening the day. It has accordingly been
suggested that it is this action of the tides which produces the
supplementary effect necessary to complete the physical explanation
of the lunar acceleration, though it would perhaps be a little
premature to assert that this has been fully demonstrated.

The third of Professor Adams' most notable achievements was connected
with the great shower of November meteors which astonished the world
in 1866. This splendid display concentrated the attention of
astronomers on the theory of the movements of the little objects by
which the display was produced. For the definite discovery of the
track in which these bodies revolve, we are indebted to the labours
of Professor Adams, who, by a brilliant piece of mathematical work,
completed the edifice whose foundations had been laid by Professor
Newton, of Yale, and other astronomers.

Meteors revolve around the sun in a vast swarm, every individual
member of which pursues an orbit in accordance with the well-known
laws of Kepler. In order to understand the movements of these
objects, to account satisfactorily for their periodic recurrence, and
to predict the times of their appearance, it became necessary to
learn the size and the shape of the track which the swarm followed,
as well as the position which it occupied. Certain features of the
track could no doubt be readily assigned. The fact that the shower
recurs on one particular day of the year, viz., November 13th,
defines one point through which the orbit must pass. The position on
the heavens of the radiant point from which the meteors appear to
diverge, gives another element in the track. The sun must of course
be situated at the focus, so that only one further piece of