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Page:Popular Science Monthly Volume 21.djvu/263

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HYDRODYNAMICS AND ELECTRICITY.

The question, "By what way and by whom was the peacock brought into Italy?" is shrouded in deep darkness; and the supposition of Hehn, that it was brought thither directly from Phœnicia or Carthage, stands upon doubtful testimony. It was, however, cordially received and prized in that country, especially in the later times of senseless luxury. The orator Hortensius, a contemporary of Cicero, was the first to bring the peacock roasted upon the table, and, despite the lack of palatableness in its flesh, his example seems to have been extensively imitated.

From Italy the peacock found its way into the rest of Europe, and became in Christian lands the subject of a double symbol. On one side it was regarded as an emblem of immortality, for the story gained credence that its flesh was incorruptible; on the other hand, it served as an exhortation to humility, according to the well-known proverb, "The peacock has a brilliant coat of feathers, but do not look down at its feet."

Reference was made, too, to its sneaking walk and its vicious character, especially in old age. But the knight gladly adorned his helmet with its feathers, and the custom at great banquets of bringing to the table, amid the flourish of trumpets, a roasted peacock adorned with its own feathers, and of taking a vow thereupon, lasted down to the end of the middle ages. In more recent times, however, the bird, together with its flesh and its feathers, has fallen into discredit; and it is left to the Chinese mandarin to carry the peacock's feathers as a sign of rank.

 

HYDRODYNAMICS AND ELECTRICITY.

VISITORS at the recent Electrical Exposition in Paris were much interested in an apparatus exhibited by Dr. C. A. Bjerknes, of the University of Christiania, Norway, for the illustration of certain properties in hydrodynamics analogous to some of the manifestations of electricity and magnetism. Professor Bjerknes has been carrying on his investigations in this line for nearly twenty years, having published his first paper, "On the Internal Condition of an Incompressible Fluid in which a Sphere of Variable Volume is moving," in 1863, and having followed it up with numerous other papers relating to similar problems. The results of experiments in every case corresponded with those which had previously been indicated to him by mathematical calculations. The experiments had in view the study of molecular movements by reproducing mechanically, but in the inverse sense, as the results proved, the simple and fundamental electrical and magnetic phenomena.

Pulsating and scillating bodies are applied so as to produce vibra-