12 Vol. XXXVir., Art. l.~K. Fuji : 



its energy by friction. Behind the electro-magnet, there is a 

 circuit-breaker for oj^iening tlie current of the electro-magnet. To 

 its level", an armature made of laminated iron is fixed, so that 

 when the armature is pushed against the electro-magnet, the 

 contact on the upper end of the lever makes the current by means 

 of which this armature as well as the armature fixed to the car is 

 kept in position at the same time, and the magnetic circuit is thus 

 closed through these armatures and the cores of the electro-magnet. 

 The service of this contrivance is twofold. When the current 

 through the electro-magnet is l;)roken at the shutter, this armature, 

 together with that of the car, is released, and the magnetic circuit 

 is broken at once, so that, on account of the increase of the 

 demagnetising force, the electro-magnet loses its magnetism very 

 soon. This is essential for the quick and unfailing action of the 

 stimulation-apparatus. The second service of this contrivance is 

 evident, for wlien once the circuit is opened at tliis place, it does 

 not close again. 



On the base-board of the stimulation-apparatus and under the 

 rails l)efore mentioned, lie three grooves each furnished with a 

 millimetre-scale along its length and each parallel to the rails. 

 Into these grooves fits any one or a combination of small mechan- 

 isms, which are put into action by the knocker attached to the car. 

 The position of tlie.-^e mechanisms can be read to one-tenth of a 

 millimetre l)y means of verniers attached to them. : 



One of these mechanisms is called a circuit-breaker and is used 

 for breaking the primaiy circuit of the induction coil. Plate V., 

 Fig. 2 shows the construction of the circuit-breaker. The circuit 

 is to be broken at tlie contact between a knock-down lever / and the 

 platinum point of an adjustable screw .9. The lever / is kept vertic- 

 aUy and ]iressed firmly against the screw by a holder h by means 

 of a spring. When the car moves leftwards, the knocker kicks down 

 the lever I and the contact is broken. The peculiar form of the 

 end of the lever and of the holder protects the former from making 

 a second contact with the screw. 



Plate v.. Fig. 3 is another mechanism which we shall call the 

 connection-changer. The rôle of this is to short circuit the secondary 



