n glass. We saw that with light weights and
when the pressure

276

{Diagram}

Diagram showing successive states obtaining in ice, before,
during, and after the passage of the skate. The temperatures and
pressures selected for illustration are such as might occur under
ordinary conditions. The edge of the skate is shown in magnified
cross-section.

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Was not sufficient to melt the ice, the friction was much the
same as that of metal on glass. Ice is not slippery. It is an
error to say that it is. The learned professor was very much
astray when he said that you could skate on ice because it is so
smooth. The smoothness of the ice has nothing to do with the
matter. In short, owing to the action of gravity upon your body,
you escape the normal resistance of solid on solid, and glide
about with feet winged like the messenger of the Gods; but on
water.

A second condition essential to the art of skating is also
involved in the melting of the ice. The sinking of the skate
gives the skater "bite." This it is which enables him to urge
himself forward. So long as skates consisted of the rounded bones
of animals, the skater had to use a pointed staff to propel
himself. In creating bite, the skater again unconsciously appeals
to the peculiar physical properties of ice. The pressure required
for the propulsion of the skater is spread all along the length
of the groove he has cut in the ice, and obliquely downwards. The
skate will not slip away laterally, for the horizontal component
of the pressure is not enough to melt the ice. He thus gets the
resistance he requires.

You see what a very perfect contrivance the skate is; and what a
similitude of intelligence there is in its evolution. Blind
intelligence, because it is certain the true physics of skating
was never held in view by

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the makers of skates. The evolution of the skate has been truly
organic. The skater selected the fittest skate, and hence the fit
skate survived.

In a word, the possibility of skating depends on the dynamical
melting of ice under pressure. And observe the whole matter turns
upon the apparently unrelated fact that the freezing of water
results in a solid more bulky than the water which gives rise to
it. If ice was less bulky than the water from which it was
derived, pressure would not melt it; it would be all the more
solid for the pressure, as it were. The melting point would rise
instead of falling. Most substances behave in