SYMPATHETIC VIBRATIONS IN MACHINERY. 737 



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 promi- 

 nent 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 

 Vendome Column must go, because it glorified a man who was the in- 

 carnation of the war-spirit, and who was consequently the worst foe 

 of the working-classes. To a select committee of the House of Com- 

 mons 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 Hemew. 







SYMPATHETIC VIBKATIONS IN MACHINERY. 1 



By Prof. J. LOVEEING, 



OP HARVARD COLLEGE. 



AT the meeting of this Association in Burlington, I showed some 

 experiments in illustration of the optical method of making sen- 

 sible 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. 

 VOL. III. 47 



