If he is alone, he will be lucky if he gets home at all--and any one who thoroughly realises this will think twice before he goes ski-ing by himself without saying where he is going.
The advantage of carrying a map and compass, and of knowing how to use them in case of losing one's way, is obvious. It is not only the mountaineer but the ordinary tourist who is exposed to this danger, for even the latter should remember that when once he is above the tree-line a snow-storm or a fog may make it impossible for him to find his way for ten yards by eye alone.
In thick snow or fog nothing is visible except a blank whiteness. When the fog or falling snow are thin, objects which are darker than the snow (rock, trees, &c.) may be visible for some distance, but all light and shade disappears in the snow itself, all tracks, holes, and irregularities in its surface become quite invisible, and it is then impossible, in a bare tract of snow, for the runner to tell whether the ground in front of him goes downhill, uphill, or level.
Even an overcast sky causes this curious absence of light and shade; and then, though the main landmarks may be visible, and there may be no danger of getting lost, running becomes exceedingly difficult and uncomfortable, perhaps even dangerous, for the snow on the edge of a precipice or steep drop, when seen from above, is apparently continuous with the snow at the foot of it.
In the description of equipment I have already mentioned the necessary safeguards against frost-bite and snow blindness.
Anything more than an allusion to the danger from avalanche is quite beyond the scope of this book. It is an intricate subject, about which whole books have been, and no doubt will yet be, written.
I believe that even now the conditions which produce winter avalanches are not fully understood. On any open slope of more than certain steepness--23° or so--an avalanche may start, especially after a thaw, or before the snow of a recent fall has had time to settle down. An avalanche, once started, can of course travel over a less steep slope, or even level ground. Lose no time in collecting all the information you can on the subject; for, although the ordinary tourist (not the climber) can usually avoid it, the danger is a very serious one, and you should never willingly expose yourself to the smallest risk of it. If the risk is unavoidable, make sure that you can get your skis off your feet in a moment, for if you are caught in an avalanche this is the first thing to do. The next is, if possible, to keep your head above the surface of the snow.