Now, when two bodies of water, approaching each other from opposite directions, meet, if the waves of each body coincide in the time of their upward and downward movements, the resulting waves will have their amplitudes enlarged, i. E the distance from crest to crest will be enlarged; if, however, the approaching waves do not coincide in time, should the crest of one set coincide with the trough of the other set, the amplitudes of the resulting waves will be diminished; or the downward force of one set of waves meeting the upward force of the other set, the result may be a. Complete antagonism of forces and the waves may be de stroyed.