﻿160 Intelligence and Miscellaneous Articles. 



ON A FRICTION AND INDUCTION ELECTRICAL MACHINE. 

 BY F. CARRE. 



The author exhibited to the Academy of Sciences a new generator 

 of electricity founded upon statical induction reduced to its simplest 

 expression, the action of which he considers may aid in more clearly 

 defining this phenomenon. 



It consists of the friction-plate of the old electrical machine turn- 

 ing slowly between two cushions ; above and parallel to this plate 

 turns a larger disk of non-conductive matter, in such a position that 

 the superior and inferior sectors of the two plates reciprocally cover 

 from two-fifths to three-fourths of each other's radii. 



The inferior plate fulfils the function of an inductor, the charge of 

 which is kept constant by its continuous passage between the two 

 cushions ; it acquires positive electricity. In front of the inferior 

 sector of the induced disk is a vertical comb connected with a con- 

 ductor which becomes charged with positive electricity ; a second 

 comb placed diametrically collects the negative electricity which is 

 poured out upon the disk by the lower comb. 



From the direct action of the inductive plate at its maximum of 

 charge, the apparatus is but slightly sensitive to the humidity of the 

 atmosphere, and the induced disk furnishes an abundant evolution 

 of electricity of considerable tension. Sparks of 15 to 18 centimetres 

 may be obtained with a machine having plates 38 and 49 centi- 

 metres in diameter ; and the interposition of a condenser increases 

 their length. — Comptes Rendus, December 28, 1868, p. 1341. 



BY A. POPPE. 



On closely viewing the flame of an ordinary Bunsen's burner, we 

 are at once struck bythe peculiar flickering or pulsation of the flame, 

 to which any definite rhythm seems wanting. I investigated the 

 cause of this phenomenon, and the true form of the flame, by the me- 

 thod which Magnus used in his investigation on the constitution of 

 the jet of water. Between the eye and the flame is interposed a 

 circular disk, in which is cut a narrow slit in a radial direction, so 

 that the whole length of the flame is seen when the slit is parallel 

 to it. On rotating the disk, when the velocity has acquired a cer- 

 tain rapidity it will be observed that that flickering is due to an un- 

 dulatory motion, which consists in a very rapid and regular succes- 

 sion of enlargements (loops) and contractions (nodes) of the flame. 

 If the disk makes one rotation in the time required for the succeed- 

 ing wave to take the place of the preceding one, the flame appears 

 immoveable, and the true form of the flame, which is that of an un- 

 duloid with a circular section, is at once plain. From the measu- 

 rable distance of the two loops, and the given velocity of rotation of 

 the disk, the actual velocity of propagation of the wave-motion may 

 be calculated. — Poggendorif's Annalen, No. 10, 1868. 





