66 Royal Society, 



which 200 feet of copper wire, one 20th of an inch in diameter and 

 covered witli stout sewing-silk, are coiled, is made to revolve on a 

 spindle, placed in the axis of a system of horse-shoe niagnets, so as 

 to remain within the branches of the latter during its whole revolu- 

 tion. The electric currents produced in the copper wire by mag- 

 netic induction, while the coil is moved at right angles to the plane 

 of the magnets, are conducted by means of four semicircular me- 

 tallic flanges attached to the spindle, into cisterns of mercury, the 

 one being positive, and the other negative ; and which consequently 

 act as the two poles of the battery. In the second form of the ap- 

 paratus, a piece of soft iron, of which the ends are bent into the 

 shape of two arms, and which is surrounded with a coil of 300 feet 

 of copper wire, is made to revolve in front of the poles of a horse- 

 shoe magnet ; its axis of motion coinciding with that of the magnet; 

 and the electrical currents determined in the wire by this rotation, 

 being collected in the same manner as in the former instrument. 



Tlie author next details several series of experiments which he 

 made for the purpose of ascertaining the relation observable be- 

 tween different velocities of rotation in these instruments and the 

 corresponding effects : first, with regard to the deflection of a mag- 

 netic galvanometer ; secondly, with regard to chemical decompo- 

 sitions; thirdly, with regard to the production of sparks; and lastly, 

 with regard to the intensity of the shock communicated to the hu- 

 man body. He compares the effects produced by the magnetic 

 electrical battery, first, when the coil consisted of one continuous 

 length of wire ; secondly, when the coil was doubled upon itself so 

 as to constitute two sets of conductors of half the length of the 

 former ; thirdly, when, upon being again doubled, it composed four 

 conductors of one quarter of the length of the first ; and lastly, when, 

 on being doubled a third time, the electric current was made to pass 

 through eight wires, each one eighth of the original length of the 

 single wire. It was found that by thus multiplying the channels of 

 conduction, although both the magnetic and the luminous effects 

 continue to be produced with scarcely any sensible difference of 

 intensity, the power of effecting chemical decompositions becomes 

 more and more impaired, and the physiological influence is weak- 

 ened in a still more remarkable degree. In the four-stranded coil, in- 

 deed, no shock whatever could beproduced, however rapidly the in- 

 strument was made to revolve. The author endeavours to account for 

 these variations of effect by the- diminution of velocity in the elec- 

 tric current, its quantity remaining unaltered, consequent on its 

 division into several streams by the multiplied channels offered to 

 its progress. He also tried the effects of conjoining the magnetic 

 electrical machine with ordinary voltaic combinations ; sometimes 

 acting in cooperation, and at other times in opposition to one an- 

 other; and notices the corresponding results, which were sufficiently 

 accordant with theory. 



17. ♦' Welt Mechanik." By M, Kropalschek. 



The object which the author has in view, in this paper, is to over- 

 turn the theory of universal gravitation, as regulating the planetary 

 motions. The memoir is divided into two parts ; in the first, he dis- 



