234 Mr. B. Phillips on the Magnetism of Pewter Coils. 



but not above half as strong. The galvanoscope was again low- 

 ered with respect to the coil ; the swing was now to C, and 

 powerful. Finally, the galvanoscope was again lowered until 

 the needle stood m the same position with respect to the lower 

 end of the axis of the coil as it did at the commencement with 

 regard to the upper end ; the swing was to C, and equally pow- 

 erful with the corresponding swing to A. 



1G5. The coil was now arranged as usual with its axis hori- 

 zontal, having that end which before pointed to the zenith now 

 directed to the needle of the galvanoscope. The swing was to 

 A when the steam passed. 



166. The pewter coil (29.) was supported in the same position 

 as in (165.), and so arranged that the fountain [77.) could easily 

 be connected with or removed from the coil. The zinc screen 

 and galvanoscope were used as in the foregoing experiments with 

 steam ; and the water-way of the cock of the fountain, which 

 was the passage of the least diameter through which the water 

 passed, was -f^ inch across. Water was placed in the fountain 

 and made to boil, the air was then pumped in, and the fountain 

 was united with the coil. On opening the cock of the fountain, 

 and so allowing the water to flow through the coil, the needle 

 started towards A, and the swing produced was about one -third 

 the length of the scale. The fountain was immediately removed, 

 rinsed out with cold water, charged again with cold water, and 

 then reunited with the coil which was still hot. The cock of 

 the fountain now being opened, the swing was to C, and nearly 

 as strong as before. 



167. The iron core (131.) was placed in the coil. Hot water 

 now being sent through the coil produced a violent swing to A ; 

 and then, while the coil was hot, sending cold water through it 

 produced nearly as strong a swing to C ; in both instances the 

 needle vibrated across and considerably outside the field of view. 

 Sending cold water through, the coil also being cool, produced 

 no magnetic effect. 



168. These experiments show that the magnetism of the coils 

 is an effect of heat independent of condensation. 



169. A piece of stout copper wire, 4 feet 2 inches long and 

 ^ inch diameter, was covered by winding tape about it ; some 

 copper wire, -^-q inch diameter, and covered, was now wound out- 

 side the tape, and the rounds lay nearly close together without 

 overlapping. The stout copper wire, having been thus covered 

 throughout its whole length, was next wound up into a helix of 

 eleven convolutions, which did not overlap each other, and the 

 internal diameter of the coil was 1*3 inch. The cuiTcnt from 

 a galvanic battery being transmitted through the fine copper wire, 

 caused this compound helix to possess similar magnetic proper- 

 ties to those of the pewter coils. 



