the downward movement of glaciers (510/1. Canon Henry Moseley, "On
the Mechanical Impossibility of the Descent of Glaciers by their Weight
only." "Proc. R. Soc." Volume XVII., page 202, 1869; "Phil. Mag." Volume
XXXVII., page 229, 1869.): if he is right, do you not think that the
unknown force may make more intelligible the extension of the great
northern ice-cap? Notwithstanding your excellent remarks on the work
which can be effected within the million years (510/2. In his paper
"On Geological Time, and the probable Date of the Glacial and the Upper
Miocene Period" ("Phil. Mag." Volume XXXV., page 363, 1868), Croll
endeavours to convey to the mind some idea of what a million years
really is: "Take a narrow strip of paper, an inch broad or more, and 83
feet 4 inches in length, and stretch it along the wall of a large hall,
or round the walls of an apartment somewhat over 20 feet square.
Recall to memory the days of your boyhood, so as to get some adequate
conception of what a period of a hundred years is. Then mark off from
one of the ends of the strip one-tenth of an inch. The one-tenth of an
inch will then represent a hundred years, and the entire length of the
strip a million of years" (loc. cit., page 375).), I am greatly troubled
at the short duration of the world according to Sir W. Thomson (510/3.
In a paper communicated to the Royal Society of Edinburgh, Lord Kelvin
(then Sir William Thomson) stated his belief that the age of our planet
must be more than twenty millions of years, but not more than four
hundred millions of years ("Trans. R. Soc. Edinb." Volume XXIII., page
157, 1861, "On the Secular Cooling of the Earth."). This subject has
been recently dealt with by Sir Archibald Geikie in his address as
President of the Geological Section of the British Association, 1899
("Brit. Assoc. Report," Dover Meeting, 1899, page 718).), for I
require for my theoretical views a very long period BEFORE the Cambrian
formation. If it would not trouble you, I should like to hear what you
think of Lyell's remark on the magnetic force which comes from the sun
to the earth: might not this penetrate the crust of the earth and then
be converted into heat? This would give a somewhat longer time during
which the crust might have been solid; and this is the argument on which
Sir W. Thomson seems chiefly to rest. You seem to argue chiefly on
the expenditure of energy of all kinds by the sun, and in this respect
Lyell's remark would h