Page:Popular Science Monthly Volume 23.djvu/512

496 sea in which they are formed. Thus the largest surface of water to be found on the earth is in the latitude of the Cape of Good Hope; and the strongest waves are met in the neighborhood of this cape. In the Mediterranean the wave is short.

In all ages men have sought for means of calming the agitation of the waves, which is so prejudicial to shipping. The best means hitherto employed has been that of breakwaters, the operation of which is too well known to need description. It may be added that floating wave-breaks, such as would be constituted by a large number of spars or planks left to drift, afford a perfect amelioration of the agitation of the waves. Hitherto engineers have applied their efforts only against the larger waves. Why not attack the evil in its origin? Why not take up the ripples and the wavelets, and oppose them with floating ripple-breaks? Such breaks might be made with twigs, saw-dust, or soot, etc., and experiment has proved that they will be efficacious. The needles of ice which form in cold weather on the surface of the water are excellent natural wavelet-breaks. Generally, every cause hindering the formation of wavelets appeases the agitation of the waves. Thus a rain, every drop of which breaks a ripple, calms the sea to a certain extent. Sailors know this. Billows have been fought against with ordinary wave-breaks. Wavelets may be destroyed by employing light bodies, ripples with dust, microscopic ripples with an infinitely fine powder. A liquid will serve the end admirably. Oil is the best of all agents for the purpose. It has the property (to which capillarity is probably not foreign) of spreading over the water as a pile of billiard balls spreads over a well-polished marble table. Its molecules form as many floating microscopic pebbles, in the intervals between-which the ripples break, as the billows break upon the shingle of the coasts. Oil thus acts as a lubricant, attenuating the friction of the wind. Capillary phenomena, due to the minuteness of the intervals between the oleaginous molecules, intervene to divide up and draw off the surface of the water and completely neutralize the force of the wind. All of these causes together may give us the reason of the efficacy of oil in destroying waves.

It should be understood that all the means of restraining the agitation of waves here indicated are good only against direct waves due to the formation of ripples. They have but slight influence on waves of transmission, which are due to other causes. Oil may appease the billows, but the swell will continue.—Translated for the Popular Science Monthly from La Nature.