234 [Dec. 12, 



a wire, the crispations became about one-half their previous width 

 and more steady ; the sounds also increased in loudness, and their 

 tone rose considerably. On gradually increasing the number of 

 elements from three to ten, and at the same time gradually diminish- 

 ing their depth of immersion to f ths of an inch, these effects of the 

 closed secondary circuit gradually and considerably diminished, and 

 ceased altogether when twenty Smee's elements, 2J- inches wide, and 

 immersed about 1 or 2 inches, were employed. If the current from 

 the ten large elements was passed through the fine or secondary wire 

 of the coil, and a very small phonetic cathode of mercury |- an inch 

 long and yjyth of an inch wide, similar effects were obtained on 

 closing the circuit of the inner coil of large wire. 



39. On inserting a cylindrical bundle of iron wires, 6 inches long 

 and If inch diameter, in the axis of the coil of Experiment 2 (34), 

 the coil being in circuit with a phonetic vessel, and three Smee's 

 elements, the crispations became a little wider and the sounds a little 

 more base. Also one length, 152| feet of "No. 17" copper wire, 

 wound upon the massive soft iron ring of Experiment 3 (34), in 

 circuit with seven elements, immersed 8^ inches, and a phonetic 

 liquid, lowered the tone of the sounds much more than a coil of 13 7J 

 feet of " No. 19 " copper wire containing no iron core. Much more 

 conspicuous effects of the presence of an iron core were obtained as 

 follows : The coil of Experiment 2 (34) was connected in circuit 

 with two Smee's elements immersed 8J inches, and a phonetic ring 

 1 1 inch external diameter and ^th of an inch wide ; very narrow 

 crispations occurred, which lasted only about ten seconds ; but on 

 inserting the cylindrical bundle of wires, the crispations became 

 double their previous width, and the sounds baser and long con- 

 tinued. And in a second experiment with the coil connected as a 

 double wire 136 feet long, without the core the crispations were con- 

 tinuous and rather narrow, and with the core they were much more 

 coarse and the sounds more feeble. 



40. But the most decisive effects, both of core and secondary coil, 

 were obtained with a moveable core 8J inches long and 2 inches 

 diameter, containing 6 Ibs. of size "No. 32" annealed iron wires ; a 

 primary coil consisting of 240 feet of double copper wire, size 

 " No. 17," in circuit with four Smee's elements (4) connected as two 

 pairs, and a secondary coil containing 4243 feet of "No. 26" 



