As waves are among the interesting things in the world, partly on account of their living quality and partly because of their immediate and often exceeding interest to man, we may here note one or two peculiar features in their action. In the first place, as the reader who has gained a sense of the changes in form of action may readily perceive, the beating of waves on the shore converts the energy which they possess into heat. This probably warms the water during great storms, so that by the hand we may note the difference in temperature next the coast line and in the open waters. This relative warmth of the surf water is perhaps a matter of some importance in limiting the development of ice along the shore line; it may also favour the protection of the coast life against the severe cold of the winter season. The waves which successively come against the shore in any given time, particularly if a violent wind is blowing on to the coast, are usually of about the same size. When, however, in times of calm an old sea, as it is called, is rolling in, the surges may occasionally undergo very great variations in magnitude. Not infrequently these occasional waves are great enough to overwhelm persons who are upon the rocks next the shore. These greater surges are probably to be accounted for by the fact that in the open sea waves produced by winds blowing in different directions may run on with their diverse courses and varied intervals until they come near the shore. Running in together, it very well happens that two of the surges belonging to different sets may combine their forces, thus doubling the swell. The danger which these conjoined waves bring is obviously greatest on cliff shores, where, on account of the depth of water, the waves do not break until they strike the steep. * * * * * Having considered in a general way the action of waves as they roll in to the shore, bearing with them the solar energy which was contributed to them by the winds, we shall now take up in some detail the work which goes on along the coast line--work which is mainly accomplished by wave action.