The skill of a rock-climber is shown by his choice of handholds and footholds and his adhesion to those he has chosen. Much depends on a correct estimate of the firm ness of the rock where weight is to be thrown upon it. Many loose rocks are quite firm enough to bear a man's weight, but expe rience is needed to know which can be trusted, and skill is required in transferring the weight to them without jerking. On all difficult rocks the rope is the greatest safeguard for all except the first man in the ascent, the last in the descent. In such places a party of three or four men roped together 15 or 20 ft. apart will be able to hold up one of their number if only one moves at a time and the others are firmly placed and keep the rope tight between them, so that the fall of an individual may be arrested before his velocity is too great. In very difficult places help may be obtained by throwing a loose rope round a projection above and pulling on it ; this method (abseil) is specially valuable in a difficult descent and has been skilfully developed by Austrian climbers.
The rope usually employed is a strong manila cord, though flax and silk are used by some. On rotten rocks the rope must be handled with special care lest it should start loose stones on to the heads of those below, and similar care is needed for hand holds and footholds. When a horizontal traverse has to be made across difficult rocks, a dangerous situation may arise unless there be firm positions at both ends of the traverse. Even then the end men gain little from the rope. Mutual assistance on hard rocks takes all manner of forms ; two or even three men climbing one upon another's shoulders or holding up an ice axe to form a foot hold for the leader. The great principle is that of co-operation, all the members working with reference to the others and not as independent units; each when moving must know what the man in front and the man behind are doing. After bad weather steep rocks are often found covered with a veneer of ice (verglas) which may even render them inaccessible. Climbing irons (cram pons, steigeisen) are useful on such occasions.
Crampons are also most useful on ice or hard snow, as by them step-cutting can be reduced and the footing at all times rendered more secure. True ice-slopes are rare in Europe though common on tropical mountains, where newly fallen snow quickly thaws on the surface and becomes sod den below, so that the next night's frost turns the whole into a mass of solid ice. An ice-slope can only be surmounted by step cutting. For this an ice-axe is needed (pickel, piolet), the com mon form having a steel head with an adze-like blade on one side and a long spike on the other at the end of a stick as long as from the elbow to the ground. This serves also as a walking-stick
and is furnished with a spike at the foot. Snow slopes are very common and usually easy to ascend. A big crevasse called a bergschrund is often found at the point where the steeper final slopes join the glacier or snowfield. Such schrunds are generally too wide to stride across and a snow bridge must be sought, not to be crossed without careful testing and a painstaking use of the rope. A steep snow-slope in bad condition may come away bodily in the shape of an avalanche. Such slopes are less dangerous if ascended directly rather than obliquely; for a line of steps cross ing the slope tends to sever it and cause a part to break away. New snow lying on ice is specially dangerous. Experience is needful for deciding on the advisability of advancing over snow in doubtful condition. Snow on rock is usually rotten unless it be thick; snow on snow is likely to be sound. A day or two of fine weather brings snow into sound condition. Snow cannot lie at very steep angles, and seldom exceeds an angle of 40°, though it often deceives the eye. Ice-slopes may be much steeper. In early morning snow is usually hard and safe, but in the of afternoon quite soft and possibly dangerous; hence on big mountains a large portion of the work is done before dawn.
These are the slits or chasms formed in the substance of a glacier, mainly at right angles to its line of move ment as it passes over an uneven bed. They may be open or hidden. In the lower part of a glacier they are open. Above the snowline they are frequently hidden by arched-over accumulations of snow and the detection of them then requires care and expe rience. After fresh snow they can only be discovered by sound ing with the pole of the ice-axe, or by looking to right and left where the extension of a hidden crevasse may be traceable. The safeguard against accidents is the rope and no one should ever cross a snow-covered glacier unless roped to one, or better to two, companions.
Cold and wet bring the menace of frostbite to toes and fingers, but the main group of dangers caused by bad weather centres in the changes it makes in the condition of snow and rock, making ascents suddenly perilous which before were easy and so altering the aspect of things as to make it hard to find the way or retrace a route. Speed is of vast importance as giving the weather less time for change, so that, broadly speaking, the diffi culty of a mountain varies as the height and distance of its sum mit from the nearest bed. In storm the man who can work by compass has great advantage over a merely empirical follower of his eyes. In large snowfields it is, of course, easier to go wrong than on rocks, but a trained intelligence is the best companion and the surest guide.