268 PLEASANT WA YS IK SCIENCE. 



the ' S. S. Cox '), ' the City of New York,' ' Senator Morton,' 

 ' the Senate has resolved to print a thousand extra copies,' 

 ' the Americans in London have resolved to celebrate the 

 coming Fourth of July.' All this my own ears heard spoken 

 to me with unmistakable distinctness by the thin circular 

 disc armature of just such another little electro-magnet as 

 this which I hold in my hand. The words were shouted 

 with a clear and loud voice by my colleague judge, Professor 

 Watson, at the far end of the line, holding his mouth close 

 to a stretched membrane, carrying a piece of soft iron, which 

 was thus made to perform in the neighbourhood of an 

 electro-magnet, in circuit with the line, motions proportional 

 to the sonorific motions of the air. This, the greatest by 

 far of all the marvels of the electric telegraph, is due to a 

 young countryman of our own, Mr. Graham Bell, of Edin- 

 burgh, and Montreal, and Boston, now about to become a 

 naturalized citizen of the United States. Who can but 

 admire the hardihood of invention which devised such very 

 slight means to realize the mathematical conception that, if 

 electricity is to convey all the delicacies of quality which 

 distinguish articulate speech, the strength of its current must 

 vary continuously, and as nearly as may be in simple pro- 

 portion to the velocity of a particle of air engaged in con- 

 stituting the sound ? " 



Since these words were spoken by one of the highest 

 authorities in matters telegraphic, Professor Bell has intro- 

 duced some important modifications in his apparatus. He 

 now employs, not an electro-magnet, but a permanent 

 magnet. That is to say, instead of using at each station 

 such a bar of soft iron as is shown in Fig. 6, which becomes 

 a magnet while the electric current is passing through the 

 coil surrounding it, he uses at each station a bar of iron 

 permanently magnetized (or preferably a powerful magnet 

 made of several horse-shoe bars that is, a compound 

 magnet), surrounded similarly by coils ot wire. No battery 

 is needed. Instead of a current through the coils magnetiz- 

 ing the iron, the iron already magnetized, causes a current 



