408 



Electro -magnetic 



£x 



xpermienU. 



tions, and particularly that of substituting cotton well waxed for silk 

 thread, which in these investigations, became a very considerable emit 

 of expense ; he also made a number of experiments with iron bonnet 

 wire, which, being found in commerce already wound, might possibly 

 be substituted in place of copper : — the result was that with very short 

 wire the effect was nearly the same as with copper, but in coils of long 

 wire with a small galvanic element it was not found to answer ; Dr. 

 Beck also constructed a horse-shoe of round iron, one inch in diame- 

 ter, with four coils on the plan before described ; Avith one wire it 

 lifted 30 lbs., with two wires 60 lbs., with three wires 85 lbs,, and with 

 four wires 112 lbs. 



"While engaged in these investigations, the last No. of the Edin- 

 burgh Journal of Science was received, containing Prof. Moll's paper 

 on Electro-Magnetism, some of his results are, in a degree, similar to 

 those here described : his object, however, was different, it being on- 

 ly to induce strong magnetism on soft iron Vv^ith a powerful galvanic 

 battery. The principal object in these experiments was to produce 

 the greatest magnetic effect, with the smallest quantity of galvan- 

 ism. The only efiect Prof. Moll's paper has had over these investi- 

 gations, has been to hasten their publication : the principle on which 

 they were instituted was known to us nearly two years since, and at 

 that time exhibited to the Albany Institute. 



A, the magnet covered with linen, the ends of the wires projecting so as to be sol- 

 dered to the galvanic element B. C, a cup Vv'ith dilute acid on a moveable shelf. 

 D, a graduated lever. E, a counterpoise. F, ascale for supporting weights ; when 

 a small sliding weight on the lever is not used ; a second galvanic element is attached 

 to the appparatus so that the poles of the magnet can he instantly reversed, this is 

 omitted in the figure. 



By inverting the large magnet, it sets in motion a very large revolving cylinder of 

 March and Ampere. 



