THE ELECTEIG LIGHT. 429 



January 1, 1872. At the Lizard, which enjoys the 

 newest, and most powerful development of the electric 

 light, it began to shine on January 1, 1878. 



I have now to revert to a point of apparently small 

 moment, but which really constitutes an important 

 step in the development of this subject. I refer to the 

 form given in 1857 to the rotating armature by Dr. 

 Werner Siemens, of Berlin. Instead of employing coils 

 wound transversely round cores of iron, as in the 

 machine of Saxton, Siemens, after giving a bar of iron 

 the proper shape, wound his wire longitudinally round 

 it, and obtained thereby greatly augmented effects 

 between suitably placed magnetic poles. Such an 

 armature is employed in the small magneto-electric 

 machine which I now introduce to your notice, and for 

 which the institution is indebted to Mr. Henry Wilde, 

 of Manchester. There are here sixteen permanent 

 horse-shoe magnets placed parallel to each other, and 

 between their poles a Siemens armature. The two 

 ends of the wire which surrounds the armature are now 

 disconnected. In turning the handle and causing the 

 armature to rotate, I simply overcome ordinary me- 

 chanical friction. But the two ends of the armature 

 coil can be united in a moment, and when this is done 

 I immediately experience a greatly increased resistance 

 to rotation. Something over and above the ordinary 

 friction of the machine is now to be overcome, and by 

 the expenditure of an additional amount of muscular 

 force I am able to overcome it. The excess of labour 

 thus thrown upon my arm has its exact equivalent in 

 the electric currents generated, and the heat produced 

 by their subsidence in the coil of the armature. A 

 portion of this heat may be rendered visible by con- 

 necting the two ends of the coil with a thin platinum 



