1861.] 233 



copper wire (i. e. 300 or 400 feet of sizes "Nos. 10 to 14"), con- 

 taining a massive iron core, enlarged the phonetic range of battery 

 power in each direction ; it enabled a less number of elements and a 

 less surface of plate to produce continuous sounds, and also enabled 

 a larger surface of the largest number (10) to be used ; in the latter 

 case it probably acted in part by diminishing the quantity of elec- 

 tricity. 2nd. An extreme length of thick wire (equal to between 

 900 and 1000 feet of size "No. 12 "), coiled upon massive iron, also 

 enabled a less number of elements to produce a continuous sound, 

 but the vibrations were wider and the sounds much more feeble than 

 with a medium length. And, 3rd. A short length of thick wire (30 

 feet of size "No. 10") without an iron core, or a long length of 

 thin wire (154 feet of size " No. 26 ") without an iron core, did not 

 enable a smaller number of elements to produce continuous sounds. 

 With a small number of large elements, and a coil of thick wire to 

 assist in developing the crispations, it was frequently the case that 

 the sounds did not occur for a short time ; and in still feebler cases 

 the mercury required the assistance of mechanical disturbance (22) to 

 enable the crispations and sounds to commence. It appears singular 

 that although a coil of wire must make the current more feeble, it 

 should enable a battery to produce the sounds which was already 

 too feeble to produce them. 



37. A massive unexcited thermo-electric battery of thirty pairs of 

 bismuth and antimony, interposed in the circuit with four Smee's 

 elements 7-J- inches wide and 9 inches deep, had no perceptible effect 

 upon the vibrations. A fine platinum wire 2 inches long, interposed 

 in a circuit with a battery and phonetic vessel, became red-hot, and 

 caused the vibrations to become wider, and the tone of the sound 

 lower than when the wire was excluded, probably by diminishing the 

 quantity of the current. No new effects were observed on using an 

 intermittent current from the primary wire of a small induction-coil 

 instead of the unaltered current direct from the battery. 



Influence of Induction Coils and Iron Cores. 



38. A current of electricity from three Smee's elements immersed 

 8|- inches was passed through the primary wire of a Ruhmkorff s coil 

 (without a break-hammer) and a phonetic vessel ; on closing the 

 secondary circuit by a drop of solution of iodide of potassium or by 



VOL. XII. S 



