374 Miscellaneous Intelligence. 



Finally, two vessels were then disposed on the wire, one con- 

 taining the frigorific mixture, the other boiling water; the wire 

 gave way between them, requiring the same weight as before. 



It may thus be considered as demonstrated, that between the 

 limits of temperature indicated i.e., 212° and — 8° F. ; change 

 of temperature has no influence on the tenacity of iron wire. 

 —Bib. Univ., xxii. 220. 



12. Electro-Magnetism. New Experiments by M. Seebeck on 

 Electro-Magnetic Action. — This gentleman, member of the aca- 

 demy of Berlin, has discovered that an electrical circuit can be 

 established in metals, without the interposition of any liquid. 

 The electrical current is established in this circuit by disturbing 

 the equilibrium of temperature. The apparatus for exhibiting 

 this action is very simple. It may be formed of two arcs of 

 different metals ; for example, copper and bismuth soldered to- 

 gether at the two extremities, so that together they make a 

 circle ; it is not even necessary that the metallic pieces should 

 have the form of an arc, or that their union have that of 

 a circle ; it is enough if the two metals form together a 

 a circuit ; that is, a continuous ring of any figure. To establish 

 the current, we heat the ring at one of the two places where the 

 two metals are in contact. If the circuit be composed of copper 

 and bismuth the positive electricity will assume ; in the part 

 which is not heated, the direction of the copper towards the bis- 

 muth ; but if the circuit be composed of copper and antimony, 

 the direction of the current, in the part not heated, will be from 

 the antimony towards the copper. These currents can be dis- 

 covered only by the magnetic needle, on which they exercise 

 a very perceptible influence. Henceforth we must distinguish 

 this new class of electric circuits by a significant denomination; 

 as such, the expression thermo-electric circuits, or perhaps //ter/w- 

 electric, are proposed. We can, at the same time, distinguish 

 the galvanic circuit by the name hydro-electric. — See xiv. 42. 



13. 0?i the Oscillations of Sonorous Chords. — In a science of 

 such universal interest as music, which is the object of dis- 

 cussion, not only of the musician, but of the mathematician and 

 the natural philosopher, it is remarkable what a discordance of 

 opinion there exists with regard to those sounds called harmo- 

 nics, and even with regard to the oscillations of sonorous 

 chords. The following interesting theorem removes all obscurity 

 from these subjects. 



If any two sonorous chords, A and B, be so placed, as that the 

 oscillations of one shall cause the air to act upon the other, as in 

 all stringed musical instruments, and if A oscillates, m times, 

 while B oscillates n times. ?« and n, being any whole numbers 

 prime to each other ; then, if either of these chords, as A, is 

 put in motion, the action of the air will divide B into ?n equal 



