The ascent of Mont Blanc from the Valley of Chamouni is considered, and
with justice, as the most toilsome feat that a strong man can execute in
two days. The combustion of two pounds of coal would place him on the
summit.


_The Wonders of Physics_.

What mere assertion will make any man believe that in one second of
time, in one beat of the pendulum of a clock, a ray of light travels
over 192,000 miles, and would therefore perform the tour of the world
in about the same time that it requires to wink with our eyelids, and
in much less than a swift runner occupies in taking a single stride?
What mortal can be made to believe, without demonstration, that the
sun is almost a million times larger than the earth? and that, although
so remote from us, that a cannon ball shot directly towards it, and
maintaining its full speed, would be twenty years in reaching it, it
yet affects the earth by its attraction in an inappreciable instant of
time?--Who would not ask for demonstration, when told that a gnat's
wing, in its ordinary flight, beats many hundred times in a second? or
that there exist animated and regularly organised beings, many thousands
of whose bodies laid close together would not extend an inch? But what
are these to the astonishing truths which modern optical inquiries have
disclosed, which teach us that every point of a medium through which
a ray of light passes is affected with a succession of periodical
movements, regularly recurring at equal intervals, no less than 500
millions of millions of times in a single second! that it is by such
movements, communicated to the nerves of our eyes, that we see--nay
more, that it is the difference in the frequency of their recurrence
which affects us with the sense of the diversity of colour; that, for