Now for the facts referred to above.
When a ski is pointed directly downhill and is made to slide with its sole held flat on the snow, it runs, if properly constructed, in a perfectly straight line.
If it is then “edged” to one side it runs round gradually to that side, the curved point acting against the snow like a bow rudder and drawing it to that side.
The steering effect, in theory, increases with the edging until it reaches its maximum when the ski is edged to a right angle. What happens in practice is that though the edging and the steering effect do increase together, there is no use in edging the ski beyond a certain angle—less than 45°—as, if that angle is exceeded, the ski sinks deeply into the snow and refuses to slide.
If that angle is not exceeded, however, the deeper the ski sinks into the snow (owing to the softness of the latter) the greater is the steering effect, for then a larger and more sharply curved surface of the point comes into action as a rudder.
If when going straight downhill the runner “edges” his ski—we will suppose he has only one—by simply leaning sideways, he will equally simply fall down; but if he “edges” it without leaning—if he edges it in relation to himself, so to speak—it will begin to turn; that he then leans sideways in order to keep his balance does not make the turn sharper.
If the runner traverses the slope with his ski held normally, as in [Fig. 20], b, it will run straight, for although it is then edged in relation to the slope it is not edged in relation to him. If he edges it in relation to himself it will turn more or less according as the gradient of its previous traverse has been steep or gradual.
When a ski running straight downhill is made to turn by “edging,” the further it turns, and the less directly therefore it points downhill, the less abrupt becomes the curve of its course. This curve, indeed, eventually becomes so gradual that before the ski has turned far enough to point horizontally across the slope and come to a standstill, the line of its track is practically straight.
When, therefore, a ski, traversing directly at a moderate gradient, is simply “edged” towards the slope, there is no perceptible turning effect, even if the runner does not lean inwards.
At first sight it might appear that the movement of a ski when edged and travelling in a curve would be precisely similar to that of a skate, and so it is in a way.