372 



Miscellaneous Intelligence. 



quoting tlie conclusion of the memoir of M. Savavt. The memoir 

 itself is long, and will probably engage our attention again at a future 

 time, in the progress of foreign science. 



" It results from these researches that masses of air, limited at every 

 point of their extent, or even only at part of their extent, can enter 

 into a state of vibration by communication, like those which are con- 

 tained in tubes ; and that when one is in an apartment where a sound 

 is produced, one is, as it were, in a large organ-pipe, where the 

 sonorous vibrations encountering each other, without doubt, in various 

 directions, form centres of vibration and nodal surfaces, of which the 

 form and direction vary almost infinitely, according to the form of the 

 place where the phenomenon occurs, and according to its extent and 

 the position of the different bodies which the vibrations may meet 

 with, and which by themselves may, either by acting as vibrating 

 bodies or not, influence the position of the vibrating parts and the in- 

 tensity of the motion ; for it is almost always observed in the spaces of 

 which we speak, that there are parts of the mass of air often of a very 

 small extent where the motion is incomparably stronger than else- 

 where. Nevertheless the irregularity in the distribution of the vi- 

 brating parts is not observed except in places, furnished, or of an 

 irregular form ; for in other places, and especially in long galleries, 

 the vibrating zones appear to exist generally and regularly." — Ann. de 

 Chimie, xxiv. 56". 



II. Chemical Science. 



1. Thermo-electric Rotation, by Professor Cumming. — The following 

 is an apparatus for the exhibition of thermo-magnetic rotation, in- 

 vented by Professor Cumming, and described by him in a letter to the 

 Editor of the Annals of Philosophy, N.S. 

 vi. 436". A B platina," BCFDA silver, 

 these are made into a parallelogram, 

 which is afterwards bent into a semi- 

 circular form. FE is a wire less than 

 the radius of the curve, proceeding ho- 

 rizontally from the frame, and E is an 

 agate cap by which the instrument 

 may be suspended freely on a point. 

 A lamp and magnet being placed op- 

 posite to each other are sufficient to 

 produce rotation, but the. effect is im- 

 proved by adding another magnet at 

 90° from the first, having its poles in 



the contrary direction, and being connected with it bv a bar of soft 

 iron placed beneath them. With this arrangement the rotation will 

 be from right to left, or from left to right, according to the position of 



