Page:Popular Science Monthly Volume 35.djvu/625

Rh every wave in course of formation is composed of portions the speeds of which are greatest toward the top. In a violent wind the acceleration produces on each wave a crest that becomes more and more protuberant, and at length is disintegrated, or breaks. It follows that any agent capable of preventing the washing of the superficial slices over one another will constitute an obstacle to the progressive increase of the living force of the liquid masses.

Such an agent is found in oil when it covers a sufficient extent of the surface of the sea. By virtue of its specific levity it keeps on the surface and prevents the washing of one layer of water over another. Thus is explained the soothing action, which appears so mysterious at first sight, of oils upon rough seas. Susceptible of being spread out into laminæ of the incredible thinness of $1/100000$ or $1/200000$ of a millimetre, a small quantity of oil is efficacious to cover and prevent overwashing of waves upon a large surface. When this is done, the formation of the crests or breaking waves, so dangerous to ships, can not take place, and the terrible breaker is converted into a harmless swell.



HARLES, or, more properly, Karl, King of the Franks, consecrated Roman emperor in St. Peter's, on Christmas day, 800, and known to posterity as the Great (chiefly by his agglutinative Gallicized denomination of Charlemagne), was a man great in all ways, physically and mentally. Within a couple of centuries after his death Charlemagne became the center of innumerable legends; and the myth-making process does not seem to have been sensibly interfered with by the existence of sober and truthful histories of the emperor and of the times which immediately preceded and followed his reign, by a contemporary writer who occupied a high and confidential position in his court, and in that of his successor. This was one Eginhard, or Einhard, who appears to have been born about 770, and spent his youth at the court, being educated along with Charles's sons. There is excellent contemporary testimony not only to Eginhard's existence, but to his abilities, and to the place which he occupied in the circle of the intimate friends of the great ruler whose life he subsequently wrote. In fact, there is as good evidence of Eginhard's existence, of his official position, and of his being the author of the chief works attributed to him, as can reasonably be expected in the case of a man who lived more than 