CHAPTER II.

THE THEORY OF SKATING.

SKATING, introduced undoubtedly as a pastime, then cultivated as a means of travelling over ice for the purposes of chase or trade, has again expanded once more into a charming recreation, which has gone on progressively improving to the very time we are now writing.

Philosophers years ago, when skating was in a much less advanced state, have thought it worthy of notice, from the very beautiful manner in which the curves used in figure-skating illustrate the two great forces, centripetal and centrifugal. Dr. Arnott, in his "Elements of Physics," thus most justly speaks of it: "Skating becomes to the intelligent man an intellectual as well as a sensitive or bodily treat, from its exemplifying so pleasingly the laws of motion."

Happily, at the present day, owing to the advantages of education, almost every skater, however humble his rank, has or ought to have a knowledge more or less extensive of these laws; but, nevertheless, this book might fall into the

hands of some who have it not, and yet wish to become first-rate skaters. Therefore we cannot refrain from saying to such that, to thoroughly comprehend and enjoy the many scientific beauties of our art, it is necessary to know a little at any rate of the nature of these grand laws, which so occupied the giant mind and immortalized the name of our great Newton.

Pervading, as he has shown us, the universe, and apparent as are their effects in all our daily movements per mare, per terram, these forces, it must be remembered, are in the art of skating brought into play on ice, a novel material for our progression. We shall glide smoothly over its surface, and with our body inclined at ever-varying angles, and in a manner so very different from our ordinary habits on terra firma, that we cannot imagine a few winter evenings better spent than in reading up a little of the subject, which may be found most pleasantly described in the work we have mentioned, and in many others under separate heads, or collectively under "Dynamics."

Of course some few readers will say that such knowledge as applied to skating is superfluous and unnecessary, and will remind us of the fact that it has been and can be learned without; but how few there are but would have been assisted by a competent knowledge we shall endeavour to show in the course of this work.

Notwithstanding the inevitable counterblast, then,

we shall give a few extracts from Dr. Arnott's very readable work on Physics, because in it he frequently alludes to our art. We would also refer the reader to an admirable comprehensive work on Natural Philosophy, by a senior and energetic member of our club, Mr. Brooke, a gentleman who is as fond of the difficulties of skating as of science.

65 MOTION

Is the term applied to the changing of place among bodies.

"Were there no motion in the universe, it would be dead-it would be without the rising or setting sun or river flow, or sound or light or life.

"To understand the nature and laws of the motions or changes which are going on around him is to man of the greatest importance.

"That bodies tend to continue in the state of motion or rest in which they happen to be, so as to render force necessary to change the state, is seen in the following facts. The scientific term used to express the general truth is inertia. . . .

"A man standing carelessly at the stern of a boat falls into the water behind when the boat begins to move, because his feet are pulled forward while the inertia of the body keeps it where it was, and therefore without its support. The stopping of a boat again illustrates the opposite inertia of motion by the man's falling forward.

"From the instances now given it is seen that a body at rest would never move if force were not applied, and that a body put into motion retains motion, at any rate for a time, after the force has ceased. Still there is a feeling from common experience that motion is an unnatural or forced state of bodies, and that all moving things, if left to themselves, would gradually come to rest. . .

"On more attentive consideration, however, it may be perceived that there are great differences in the duration of motions, and that the differences are always exactly proportioned to evident causes of retardation, and chiefly to friction and the resistance of the air.

"But it is in the celestial spaces that we see motion completely freed from the obstacles of air and friction, and there they slacken not.

"Force is required to bend motion. A body moving in a circle, then, or curve, is constrained to do what is contrary to its inertia. A person, on first approaching this subject, might suppose that a body which for a time has been made to move in a circle should naturally continue to do so when set at liberty. But on reflecting that a circle may be considered as made up of an infinite number of little straight lines, and that the body moving in it has its motion bent at every step of the progress, the reason is seen why constant force becomes necessary to keep it there, and just equal to the inertia with which the body tends at every point

of the circle to pursue the straight line called a tangent.

"The force required to keep the body in the bent course is called centripetal or centre-seeking force, while the inertia of the body tending outwards, that is, to move in a straight line, is called the centrifugal or centre-flying force.

"In skating with great velocity this leaning inwards at the turnings becomes very remarkable, and gives occasion to the fine variety of attitudes displayed by the expert; and if a skater in running finds his body incline to one side and is in danger of falling, he merely makes his skate describe a slight curve towards that side, and the centrifugal force of the body, refusing as it were to follow in the curve, restores the perpendicularity.

"The last example explains also why a hoop rolled along the ground goes so long without falling if it inclines to one side threatening to fall: by that very circumstance its course is bent to that side, and, like the skater who bends, it rises again; the bending of its course to either side thus brings its supporting base again under it.

"A coin dropped on the table or floor often exhibits the same phenomenon. The two great forces of nature are attraction and repulsion."

Further, there is accelerated motion from gravity, and retarded motion from gravity. Then

comes,