NATURAL PHILOSOPHY. 117 



CURIOUS PHYSIOLOGICAL PHENOMENA. 



M. Louis Luca, a Parisian scientist, lately received a select circle 

 of visitors at his house, to exhibit and explain the principle of an ap- 

 paratus of his own invention, by which a physiological fact of great 

 importance is rendered apparent, viz., the direct action of the living 

 frame on the magnetic needle. The apparatus itself is of extraordi- 

 nary simplicity. A single element of Bunssn's battery has its poles in 

 communication with an electro-magnetic bobbin, surmounted by a 

 graduated disc, bearing a magnetic needle which oscillates freely 

 round its centre, as in the common compass. This part of the appa- 

 ratus is protected by a glass shade ; the plate may be raised and 

 lowered at pleasure by a wheel and rack. The conducting wires, af- 

 ter communicating with the bobbin, branch out towards the operator, 

 and are connected together by a loose metal chain. The apparatus 

 being in this state, the needle remains perfectly quiescent, until the 

 operator takes hold of the chain either with one hand or both, when 

 the needle at once begins to move, describing arcs of from ten to 

 ninety degrees. No principle hitherto admitted into physical science 

 can account for this strange phenomenon, and we are compelled to 

 admit a physiological action capable of producing such motion. The 

 experiment was varied in many ways in our presence, and we were 

 ourselves allowed to test our individual power on the needle. That the 

 cause of the motion was of a physiological nature, was further proved 

 by the circumstance that the oscillations of the needle varied in inten- 

 sity according to the persons experimenting, and even according as the 

 same person might be differently affected either by tranquillity or a 

 warm discussion, such different states naturally modifying the suscep- 

 tibility of the nervous system. Stranger still, some persons present 

 produced the oscillations by merely touching the chain with a glass 

 rod about two metres in length, glass being, as our readers know, a 

 non-conductor. Whatever explanation may hereafter be given of 

 M. Luca's discovery, one fact seems even now indisputable, namely, 

 that the human body may directly influence the needle ; what conse- 

 quences may be evolved therefrom, time alone can show. Galignani. 



DE LA RIVE ON THE AURORA BOREALIS. 



M. de la Rive conceives that two general facts relating to the 

 aurora are established : "1st, the coincidence between the appear- 

 ance of the Boreal and the Austral auroras ; 2d, that auroras are 

 atmospheric phenomena which take place within the limits of the at- 

 mosphere, but not beyond it." He seeks to show that the positive 

 electricity carried to high regions of the atmosphere by vapors from 

 tropical seas, and which the trade-winds accumulate near the polar 

 regions, acts by induction on the negative electricity with which the 

 earth is charged. There results, he says, " a condensation of con- 

 trary electricities in those portions of the earth and of the atmosphere 

 which are nearest each other, and in consequence a neutralization in 

 the neighborhood of the poles, which takes place under the form of 

 more or less frequent discharges as soon as their tension has reached 

 a limit which cannot be maintained. These discharges ought to take 



