CHAP, vi.] ELECTRIC HOROLOGY. 637 



When the current is interrupted, the armature is drawn back by 

 the spring I, the branches SQN bend again, and the catch leaves 

 the ratchet-wheel free. The catch b prevents the return. 



The motion is communicated to the minute wheel worked by 

 the wheel it', and a bevel wheel arrangement carries it on to the 

 hands by means of the rod K. 



The originality of Froment's regulator lies chiefly in the employ- 

 ment of the distributer SPQN. This mechanical contrivance is 

 destined to proportion the resistance to the attractive force of the 

 electro- magnet in the armature. This attraction is greatest when 

 the distance is least, that is, at the moment of contact, so that it is 

 just at the moment when the motion is about to cease that the 

 velocity of the parts attains its greatest value, which is a great dis- 

 advantage to the mechanism. But by the use of this distributer, 

 the resistance increases in the same proportion as the attraction, so 

 that the attractive force of the electro-magnet remains constant. 



The electric regulators of Bain, Ritchie, Breguet, Robert Houdin, 

 and Nollet' are as deserving of description as the above, but we 

 must limit ourselves to the preceding systems, mentioning only those 

 applications that have been made with success. At Paris, Lyons, 

 Marseilles, Brussels, Ghent, and Leipzig, the regulators of these 

 systems have been worked, and are still being worked, and show 

 the time regularly and concordantly in the different parts of these 

 towns. 



Illuminated clocks are nothing but gas reflectors, within which 

 the regulators are placed, and which have time dials on one or two of 

 their faces. Messrs. Nollet at Ghent, Detouche at Paris, and Breguet 

 at Lyons, have constructed apparatus of this kind. Fig. 418 represents 

 the outside and inside of the twenty-four illuminated clocks fixed in 

 Lyons by M. Breguet. The electro -magnets, E E', are seen to be 

 double ; they are so placed that their contrary poles face each other, 

 so that the armature M, which is magnetized, is at the same time 

 attracted by one and repelled by the other, or inversely, according as 

 the current passes in one or the other of the electro-magnets. The rod 

 T carried by it acts by means of a fork, furnished with a peg, on two 

 catches i, i' , which play the part of an escapement anchor and move 

 the teeth of a ratchet-wheel, to the axis of which the minute-hand 

 is attached. 



