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SYMPATHETIC VIBRATIONS IN MACHINERY.

to give a correct decision as to the stability of particular institutions and the strength of popular passions. General rules could not be of much avail, and they had to rely on their knowledge of human nature, their acquaintance with the forces which have been at work in history, and their own sagacity. Most likely Heine could not have given such an explanation of the grounds on which he made his predictions as would have satisfied any average jury of historical students. But he could have said that he knew the working-men of Paris; that his power of poetic sympathy enabled him to see how their minds veered toward socialism, and be also knew what forces were on the side of order; and that a mental comparison of the two made him look with certainty to a ferocious outbreak of democratic passion. Being thus sure that the storm would come, he had next to ask himself which points the lightning would strike, and he looked for the most prominent symbols of kingship, wealth, refinement, and military glory. The Tuileries would be a mark for the fury of the mob, because that was the palace of the man who had destroyed the populace. The public offices must go, because they represented what the bourgeois called order and the workmen called tyranny. The Louvre must go, for the mere sake of maddening rich people who took a delight in art. And the Vendôme Column must go, because it glorified a man who was the incarnation of the war-spirit, and who was consequently the worst foe of the working-classes. To a select committee of the House of Commons such reasons would have seemed the dreams of a moon-struck visionary, and they certainly did not admit of being logically defended. No prophecy does. The power of predicting events is the power of guessing, and those guess best who are least dependent on rules, and most gifted with the mother-wit which works with the quietude and unconsciousness of instinct.—Saturday Review.

 

SYMPATHETIC VIBRATIONS IN MACHINERY.[1]
By Prof. J. LOVERING,

OF HARVARD COLLEGE.

AT the meeting of this Association in Burlington, I showed some experiments in illustration of the optical method of making sensible the vibrations of the column of air in an organ-pipe. At the Chicago meeting I demonstrated the way in which the vibrations of strings could be studied by the eye in place of the ear, when these strings were attached to tuning-forks with which they could vibrate in sympathy; substituting for the small forks, originally used by Melde,

  1. From the Proceedings of the Twenty-first Meeting of the American Association for the Advancement of Science.