78 Intelligence and Miscellaneous Articles* 



manner by the deviations produced by the open magnet, which 

 slowly diminish. The portative force is a datum too coarse for 

 judging of these changes. 



The highest value of the constant C of Bernoulli shown by my 

 Tables is 22- 4 ; I am convinced that to seek the manufacture of a 

 magnet for which C should have a value 27 or 28 would be like 

 searching after the philosopher's stone. — Coinptes Rendus de 

 VAcademie des Sciences, Nov. 27, 1876, pp. 1017-1020. 



EXPERIMENTS ON THE SYMPATHETIC RESONANCE OF TUNING 

 FORKS. BY ROBERT SPICE. 



It is well known that a pair of forks having a vibration-number 

 of 256 (Kcenig's Ut 3 forks), show the phenomenon of sympathetic 

 resonance at distances apart varying from three to six feet. 

 Beyond six feet, special and delicate means have to be employed 

 to exhibit their resonance. 



It is also well known that a pair of forks having a vibration 

 number of 512 (Ut 4 forks), exhibit the phenomenon with similar 

 intensity at far greater distances. The accepted solution of this 

 difference of deportment is, that as in the latter case double the 

 number of impulses are delivered in a second, consequently double 

 the energy is conveyed to the distant fork. 



If this explanation be sufficient, the following result should 

 follow : — Forces radiating from a centre obey the law of inverse 

 squares ; hence, if the amount of motion (or force ?) received by 

 an Ut 3 fork at a distance of six feet from its excited fellow be re- 

 presented by n, then (assuming an Ut 4 fork to have double the 

 energy of an Ut 3 fork) clearly the amount of motion received by 

 an Ut 4 fork at a distance of twelve feet from its excited fellow, 



should be represented by ~. But so far is this from being the 



case, that the intensity instead of being one-half (as calculated), 

 is more than double. In fact, at twenty feet the intensity of re- 

 sonance of Ut 4 forks is undoubtedly greater than the intensity of 

 Ut 3 forks at six feet. 



A pair of forks were cast in a kind of bell-metal, and tuned to 

 Ut 3 . On Ivoenig's boxes the resonance was quite obvious at 

 twenty feet, and at forty feet the responding fork drove a cork 

 ball of 8 mm diameter a distance of 10 mm ! This result was greater 

 than that obtained with the steel Ut 4 forks of Kcenig. In view of 

 these facts, it seemed to me that a different explanation was re- 

 quired to clear up the difficulty; and, after a careful experimental 

 examination of the question, I offer the following hypothesis : — 



The intensity of sympathetic resonance of forks on their cases 

 increases with the angular deviation or motion of the prongs. 



The question of number of vibrations per second has its proper 

 value ; but this value is small compared with the element above 

 stated. 



