232 [Dec. 12, 



wider, the sound baser and more feeble. With three elements only 

 and the total length (6 1 0^- feet) of wire in the circuit, the crispations 

 were coarse and the sounds very feeble ; and on adding to the length 

 of the wire by interposing an electro-magnet* containing 390 feet 

 of "No. 12" copper wire, the vibrations and sounds were scarcely 

 perceptible. With twenty Smee's elements, 2 inches wide and ^ inch 

 deep, crispations -^th of an inch wide occurred, and were un- 

 affected by introducing 240 feet of coiled double copper wire (size 

 "No. 17") into the circuit ; whilst with four Smee's, 7J inches wide 

 and 9 inches deep, the crispations were ^nd of an inch wide, and 

 instantly became ^jth of an inch wide on introducing the 240 feet 

 of double wire into the circuit; and with a single Grove's cell, 

 platinum plate 18 inches deep and 12 inches wide, a high and very 

 feeble sound occurred (without visible crispations unless the pool 

 formed the cathode) ; but on interposing the 240 feet of double wire, 

 crispations of moderate width at once occurred in the ring, and 

 evolved a loud sound. Other similar experiments yielded similar 

 results. In all cases the greater the length of the wire (and appa- 

 rently also the smaller its diameter) up to a certain limit, the louder 

 and more steady were the sounds ; and beyond that the feebler were 

 the sounds, until at length both vibrations and sounds entirely ceased. 



35. It was repeatedly observed that the smallest number of Smee's 

 elements, immersed 8| inches, with which the sounds could, under 

 ordinary circumstances, be produced, was three ; but on interposing 

 the primary wire of a Ruhmkorff's coil in the circuit, or the wire of 

 the electro-magnet (34 *), continuous vibrations and sounds were ob- 

 tained with only two elements ; and with the same battery and a 

 mixed gas voltameter t in the circuit, it required seven to produce 

 sounds without the coil, and five with it. 



36. To further examine the influence of coils of wire upon the 

 range of battery power which might be employed, I made a number of 

 experiments, which are not necessary to be described in detail, as they 

 are all of a similar character to those just described (34, 35) ; the 

 results are as follows: 1st. The introduction of a suitable coil of 



* The electro-magnet consisted of a horseshoe 14 inches from poles to bend, 

 formed of a cylindrical bar 1| inch thick. 



f The voltameter contained 33 square inches of acting surface of platinum in 

 each electrode, and was filled with a mixture of 1 measure of pure sulphuric 

 acid and 3i measures of distilled water. 





