Intelligence and Miscellaneous Articles. 239 



of figure " (as Plateau calls them), giving origin to periodical fluc- 

 tuations of intensity, depending on the sonorous pulses. 



If this view is correct, will it not be necessary for us to modify 

 our ideas in rekition to the agency of tubes in developing musical 

 sounds by means of burning jets of gas ? Must we not look upon 

 all burning jets, — as in the case of water-jets, — as musically inclined ; 

 and that the use of tubes merely places them in a condition favour- 

 able for developing the tones r It is well known that burning jets 

 frequently emit a singing sound when they are perfectly /yee. Are 

 these sounds produced by successive explosions analogous to those 

 which take place in glass tubes ? It is very certain, that under the 

 influence of molecular forces, any cause which tends to elongate the 

 flame, without aff'ecting the velocity of discharge, must tend to ren- 

 der it discontinuous, and thus bring about that mixture of gas and 

 air which is essential to the production of the explosions. The in- 

 fluence of tubes, as well as of aerial vibrations, in establishing this 

 condition of things is sufficiently obvious. Was not the " beaded 

 line" with its succession of "luminous stars," which Prof. Tyndall 

 observed when a flame of olefiant gas burning in a tube was ex- 

 amined by means of a moving mirror, an indication that the flame 

 became discontinuous, precisely as the continuous part of a jet of 

 water becomes shortened, and resolved into isolated drops, under the 

 influence of sonorous pulsations ? But I forbear enlarging on this very 

 interesting subject, inasmuch as the accomplished physicist last 

 named has promised to examine it at a future period. In the hands 

 of so sagacious a philosopher, we may anticipate a most search- 

 ing investigation of the phenomena in all their relations. In the 

 mean time, I wish to call the attention of men of science to the view 

 presented in this article, in so far as it groups together several classes 

 of phsenomena under one head, and may be considered a partial 

 generalization. — From Silliman's American Journal for January 1858. 



ON A NEW SOURCE OF ELECTRICAL EXCITATION, 

 BY MRS. ELISHA FOOTE. 



I have ascertained that the compression or the expansion of 

 atmospheric air produces an electrical excitation. So far as I am 

 aware, this has not been before observed, and it seems to me to 

 have an important bearing on the explanation of several atmospheric 

 and electrical phaanomena. 



The apparatus used was an ordinary air-pump of rather feeble 

 power, and adapted either to compress or exhaust the air. Its re- 

 ceiver was a glass tube about 22 inches in height and 3 in diameter, 

 with its ends closed by brass caps cemented to it. At the bottom 

 was a stopcock and a screw l)y which it was attached to tlie air- 

 pump. To the top were soldered two copper wires, one hanging 

 down within tlie tube, terminating in one or more points, and ex- 

 tending to within about G inches of the bottom, the other extending 

 from the ujjper side of tlic cap to an ordin;u-y electrical condenser. 



In experimenting after compressing or exhausting the air within 

 the receiver, the wire reaching to the condenser was disconnected 



