Ski-jumping no doubt arose from the discovery that a slight inequality
of the surface would sometimes cause a ski-runner moving fast downhill
to leave the ground involuntarily for a moment. Some abnormal person
having liked the feeling and wanted more of it, it is easy to see how
his endeavour to accentuate the inequality, and so lengthen the jump,
would lead him to construct a horizontal platform projecting from the
hillside.
A competition jumping-hill at the present day is chosen, as to shape,
and so arranged that the jumps may be as long as possible and the
jumper may have a minimum of difficulty in keeping his feet on landing.
Fig. 44 shows the usual form of the hill and position of the platform.
(See Frontispiece.)
The jumper starts at A and runs off the edge of the platform B into the
air; landing on the slope below at C, he runs down it and out on the
level, where he swings to a standstill at D.
The gradient of the hill above the platform is preferably not more than
20° or so, for the jumper must above all things be perfectly steady as
he leaves the platform, and if the upper part of the hill is very steep
the sudden change of gradient as he runs on to the platform is likely
to upset his balance. The impetus can therefore be obtained more safely
from a long run at a moderate gradient than from a short steep one.
[Illustration: FIG. 44.]
The steeper the slope below the platform, other things being equal, the
longer obviously will the jump be, and also the less will be the shock
to the jumper as he lands, on account of the narrower angle between the
ground and his course through the air. For this reason a steep gradient
below the platform is an advantage, and on big jumping-hills the angle
of this part of the slope is from 25° to 35°.
The dotted line in the diagram shows how, if the platform were placed
just at the point where the slope becomes steeper, the length of the
jump would be greater than if, as is usually the case, the platform
were built farther back; at the same time, however, the shock to the
jumper on landing would be increased also, for his course through the
air the moment before alighting would then be more directly downwards,
and when in the air he would, at his highest point, be farther from the
ground.
This is one reason why the platform is usually placed farther back.
There is sometimes another reason. The gradient must remain the same
for a sufficient distance below the point where the jumper lands to
enable him to get a steady balance on landing, and unless the steep
part of the slope is very long, it may only be possible by putting the
platform farther back to ensure that the jumper shall not land too near
the bottom of the hill.
For the same reason (of making things easier for the jumper) the change
of angle between the top part of the hill and the platform, and also
between the lower part and the level outrun, should take place as
gradually as possible.
The preceding description shows what form of hill is most desirable,
and is always chosen for competition purposes where big jumps are to be
made. It is by no means on a hill of this shape alone that a jump can
be made; and for learning, when you will only jump a short distance,
almost any hill will do, provided the ground be fairly smooth and the
slope below the platform and the level outrun beyond it be long enough.
If the shape of the hill in section is convex, as in the diagram, the
best place for the platform, as already explained, is at or near the
point where the angle changes, _provided always that the steeper part
of the hill is fully ten yards longer than the longest jump you will
make_. If it is a little less than this, build the platform farther
back; if much less, choose a slope where there is no change of gradient.
The slope below the platform, or, at any rate, all of it except the
part which the jumper would be certain to clear, must be free from
irregularities, have a good covering of snow (at least a foot _when
beaten down_), and fall at a steady gradient of not less than 20° for
choice--if possible of more.
The platform itself may be built in different ways; the high platforms
used in competitions are generally built of planks supported at the
outer corners by posts.
This is unnecessary in the case of a low platform, such as you will use
at first.
A simple way of making it, if the materials are handy, is to lay two
or three planks on top of an old packing case, and then to shovel
snow over them. Another way is to stand two short sticks upright in
the snow at the same level, and a yard or so apart, according to the
intended width of the platform. Stack fir branches against them on the
uphill side, and then build a platform of snow, or alternately snow
and branches, piling it high enough to rise well above the tops of the
upright sticks. Beat it down with the spade and stamp it with the skis
until it is quite solid.
For learning, the platform should at first be quite low--not much more
than a foot high at its front edge.
For big competitions, the platform is generally 6 or 8 feet high, or
even more, though Huitfeldt, a Norwegian authority, says it should
hardly exceed 3 feet.
Raising the platform, while increasing the length of the jump, also
increases the shock of landing, and therefore the difficulty of the
jump. This difficulty, however, depends far less on the _height_ of the
platform (which may, so to speak, be merely a negative quantity, for of
course it is possible to make the platform _look_ high by cutting away
the hillside below it without affecting the nature of the jump) than
upon the _difference between the angle of its surface and that of the
slope below_, the most difficult kind of platform to jump from being
that called by the Norwegians a "Spraet Hop" (squirt jump), which is
higher at its front edge than where it joins the hillside. At first,
therefore, make the platform at almost the same angle as the slope
below, and join it gradually to the slope above, so that there is no
sudden change of gradient.
The length of the jump depends not only on the height, position, and
angle of the platform _in relation to the slope_, but also on its
_absolute_ angle in space. Other things being equal, a platform sloping
_downwards_ at an angle of between five and ten degrees permits the
longest jumps. It would be easy to find by experiment exactly the most
favourable angle, and, for all I know, this may already have been done.
The platform's width, for practice, need be no more than a yard: for
competitions, when the jumper may wish to take a fresh track, it is
about 4 yards.
Its length of course depends on its height, and on the angle that it
makes with the slope above it. Roughly speaking, for a small jump the
platform would be 2 or 3 yards long; for a big competition one at least
6 yards.
The top of the platform must, of course, be horizontal in transverse
section; take care to build it up well at the sides in order to prevent
any convexity in the middle which might cause the jumper to side-slip
while taking off. Carefully stamp down the snow not only on the
platform, but also up the track above it for 10 or 15 yards from the
platform's edge.
This stamping should leave the snow as firm and smooth as possible, but
on the surface there should be just enough loose snow to give steerage
way and prevent side-slip. Stamping with the _edges_ of the skis on
the hard trodden snow will generally loosen the surface sufficiently,
otherwise it will be necessary to sprinkle loose snow over it, or
to scratch it with a rake. According to Huitfeldt, the Telemarkings
pile up the snow at the edge of the platform so as to form a shallow
ridge. He says that by waiting until they feel the fronts of their skis
touch this, they know when to make their spring, and that it helps the
forward tilt of the body which is necessary. The latter seems quite
likely, but a man who timed his spring in this way when running fast
would hardly even begin it before leaving the platform, far less finish
making it, as he actually ought to do.
The same preparation of the track is necessary below the platform from
the nearest point to it at which the jumper could possibly land to a
point several yards below the longest possible jump. Pay particular
attention here to stamping down the snow until it is absolutely firm,
and make this trodden track a good deal wider than the platform, to
avoid any possibility of the jumper landing outside it, for if the skis
sink deeply into the snow on landing, a very bad fall may be the result.
After each jump snow should be thrown into any holes made in the
track by the jumper himself or his skis, and should then be stamped
firm and smooth; any natural hollows likely to upset the jumper can
also be filled up in the same way. If, in order to prevent side-slip,
it is necessary to sprinkle the track with loose snow of a different
quality to that on the track itself, it must be thrown over the whole
track; for a small patch of new sticky snow, or of old and fast
granular snow, would suddenly alter the runner's speed and disturb his
balance.
It is better to stamp down too much of the track than too little,
for a fall on hard snow is quite harmless, if the slope is steep
enough, while in soft snow it may easily be dangerous. It is sometimes
advisable to stamp down the whole of the outrun to where the jumper
swings to a standstill.
_Equipment._--Skis for jumping should be long, strong, and fairly
heavy, and _must_ be grooved underneath. They should be but little
arched, and should not be flexible, otherwise the shock of landing
after a big jump will make them bend downwards in the middle so much as
to check the pace and pitch the jumper forwards.
Wax or polish their under surfaces as much as you like; they cannot be
too slippery for jumping.
Only those bindings are suitable for jumping by means of which the heel
end of the ski can easily be drawn up close to the foot when that is
held clear of the ground.
To carry a stick while jumping is useless, and, except for an expert on
an easy jump, is exceedingly dangerous.
_How to Jump._--Stand far enough up the track to get up a moderate
speed, and not less than 15 yards from the edge of the platform. By no
means risk running off the platform so slowly that your skis simply tip
over the edge and bury their points in the snow.
Clean your skis and start off in any way you like. If the start is
on the side of the hill, and not on a level place, the jumper often
thrusts his sticks into the snow on each side of the track, and stands
a little above them, facing straight downhill, holding himself back
by resting his weight on them. He can then, by merely letting go the
sticks, start quite steadily without altering the position of his skis.
Run in normal position until about 15 yards before the edge of the
platform; then bring the feet level, and crouch down until you reach
the position of Plate LII.
Take care that the _knees_ as well as the feet are pressed tightly
together, that the weight is well forward, and that the hands hang as
low as possible, _i.e._ with the finger-tips level with the ankles.
Unless you pay particular attention to this last point, and try to get
as low as you possibly can, it is probable that your position, while
feeling to yourself a decided crouch, will only appear to a spectator
as a rather half-hearted stoop at the knees and hips.
When this low crouch has become mechanical, you had better hold your
arms backwards in a horizontal position, but to touch your ankles first
is the best way of making sure that your position is correct.
I believe that Norwegian authorities are not agreed as to whether the
feet should be held level or in the normal position at this stage.
Huitfeldt, for instance, whom I have already quoted, says that the
Telemarkings, who invented jumping, always jump with the feet in the
normal position. However this may be, most good jumpers take the level
position, and you can safely do the same, but be sure, as you bring the
feet level, that they do not get apart.
_The "Sats."_--Take the above crouching position soon enough to be
running steadily in it with every detail correct by the time you reach
the platform, for before you reach the edge of this you must have your
whole attention free to be concentrated on the actual take off, or, as
the Norwegians call it, the "Sats."
This movement, which, if timed properly, is _completed_ at the instant
that the jumper's feet come to the edge of the platform, has two
objects--to increase the length of the jump, and to bring the jumper's
body into a position at right angles with the slope below at the moment
of landing.
The latter is the more important, for unless it is effected, the jumper
is of course bound to fall.
Now, if the surface of the platform were inclined at the same angle as
that part of the slope below it on which the jumper lands, he might
run down to the platform and into the air without ever moving from the
normal position, and though he would not increase the length of his
jump, he would have every chance of keeping his feet on landing, for
his body would be at the correct angle (Fig. 45, A).
But the platform itself, no matter how low it may be, and no matter
how steep the slope above it, is nearly always less steep than the
slope below it, often a good deal less. This, of course, means that the
jumper in making the "Sats" must not only spring, but must throw his
body forward, or he will land as in B and C, and fall instantly on his
back.
[Illustration: FIG. 45.]
It depends almost entirely on the angle of the jumper's body on landing
as to whether he shall fall or keep his balance, and that angle depends
absolutely on the way he makes the "Sats." Indeed, at the moment of
leaving the platform and completing the "Sats," the jumper usually
is almost certain whether he will stand or fall. It follows, then,
that the correct execution of the "Sats" is the most important part
of the jump. It is certainly the most difficult, and I think you will
find it much easier to overcome its difficulty if you realise at the
outset that the necessary forward tilt may be effected in two perfectly
distinct ways.
The jumper may make the "Sats" either so that he leaves the platform
tilted at exactly the angle at which he will land, or so that he is at
right angles to the platform when leaving it and changes the angle of
his body by degrees during his flight through the air. (See Fig. 46.)
[Illustration: FIG. 46.]
These two methods are none the less distinct for the fact that the
"Sats," as made by most jumpers, is a combination of the two.
By using the first method you will be far more certain of landing at
the proper angle, but will barely increase the length of your jump;
by the second you will be able to lengthen your jump to the utmost
possible extent, but will find it exceedingly difficult at first to
regulate the forward tilt accurately.
You had better, therefore, begin by practising the first method only,
and keep to that until you can jump with accuracy and certainty, when
you can little by little exchange it for the second one.
In order to make the "Sats" by the first method, you have, from the
crouching position of the first pair of figures, merely to bring your
body and thighs into line with the legs from the knees downwards;
for in the crouching position this lower part of the legs is already
inclined forward at about the angle at which you will have to land.
In straightening up, therefore, be most careful to keep your legs below
the knees, and also your feet, absolutely motionless.
When in the crouching position make sure that your knees are forced
forwards to their utmost extent, then try to imagine that they are
being held immovably in this position, and that your heels are fastened
firmly down to the skis. This will ensure your making the straightening
movement of the "Sats" from the knees upwards only, and, if you bring
your thighs and body exactly into line with the motionless lower part
of the legs, will also ensure your landing at about the correct angle,
or even slightly more forward, which will not matter.
As you straighten up, swing your arms forwards and upwards to help
the movement, which, when you are used to it, you must try to make so
smartly, and even violently, as to be almost instantaneous.
The sensation, however, will be quite different to that of an ordinary
standing long jump, in which the heels leave the ground as the jumper
crouches, and the spring is made from the toes. In this form of the
"Sats" it is very important that some of the weight should remain
on the heels, which should not be allowed to rise from the skis in
the smallest degree. You will find that any pressure on the toes
and lifting of the heels will, though it may seem unlikely, almost
certainly tend to make you finish the "Sats" in an erect instead of an
inclined position.
The accurate timing of the "Sats" is naturally most important. If it
is made too late and the knees are still somewhat bent as the jumper
leaves the platform (see Plate LIII.), the completion of the movement
in the air will push the skis below their natural line of flight,
and the jump will be shortened--not a very serious matter for the
beginner. If, however, the "Sats" be made too soon, and the jumper's
weight comes on his skis again before they have left the platform, he
will have a nasty fall forward. This need not trouble you, for you are
certain to find the greatest difficulty in managing to make the "Sats"
soon enough.
The more slowly you make the movement, the sooner you will have
to begin it, and the more difficulty you will have in timing it
accurately, but at first if you try to make it quickly you will
probably not do it correctly. I strongly advise you therefore to go
through the slow and careful practising stage, not on the jumping-hill
at all, but without skis, in your bedroom or anywhere else. Practise
this movement at any odd moment; it will soon become mechanical, and
if, before you start jumping, you have learnt to make this movement
quickly and accurately, you will have made things enormously easier for
yourself.
When practising the "Sats" without skis you will, of course, find that,
as your weight comes on your feet again at the end of the straightening
movement, you will be in the act of falling forwards. You can prevent
doing so by making a quick stride forward with one foot and dropping
into the Telemark position; but don't do this until the last possible
moment, first making quite sure that you are perfectly straight from
head to heels and inclined at a sufficient angle. See also that your
feet are held quite parallel and touching each other.
So much for the first method of making the "Sats." The second is as
follows. From the preparatory crouching position spring straight into
the air with a free, swinging action, but as strongly as possible, at
the same time giving the body a slight tilt forward, so that it becomes
more and more inclined during its flight through the air. The spring
is made from the toes this time, but instead of the legs being drawn
up as in ordinary jumping, they should be quite straight and in line
with the body as they leave the ground, and the feet should be pointed
downwards, exactly parallel and close together.
This movement (the arms are swung as before) is much like that of a
dive from a springboard; but while the diver's body has to make half a
revolution, or pass through an angle of 180° during its flight through
the air, the ski-jumper, even in the case of the most exaggerated
"squirt jump" on the steepest hill, could hardly have to change his
angle by more than 45°. The ski-jumper then would seem to have the
easier task.
The difficulty is that, whereas the diver wants to land (?) head first,
the ski-jumper would rather not, and instinctively shrinks from the
slight effort in that direction which is necessary.
The remarks in the description of the first method as to timing, &c.,
hold good here, and it is equally possible and advisable in this case
to practise without skis. When doing so you should, after your spring
into the air, land on the ground on tiptoe, tilted as much forward
as possible, with your feet just where they left the ground, and
absolutely parallel to and touching each other. A fall is avoided as
before by dropping into the Telemark position.
When the "Sats" is made very suddenly and energetically in this way,
the jumper may notice a tendency not merely to give an insufficient
forward tilt to his body as he springs, but even to tilt it slightly
backwards, so that he lands on his back with his skis in the air;
and this in spite of the fact that he may quite have overcome his
nervousness and desire to shrink back.