LAMP-LIGHTING BY ELECTRICITY. 685 



with a stop-cock, which is actuated by the reciprocating magnet. The 

 whole of this apparatus is inclosed in an air-tight metallic case, and is only 

 about 2h inches high, and 2^ inches wide at its greatest width, and is 

 screwed on to the supply-pipe in the lamp, the conductor being carried 

 down the interior of the lamp-post and laid underground, except where an 

 overhead line is admissible. 



This apparatus has two functions, one being to turn the gas on and off^ 

 and the other to light it at the point of the burner. The former is accom- 

 plished by ojDening and closing the stop-cock by means of what may be 

 called an electric needle-tap, and the latter by the induction coil, the whole,, 

 however, being in combination. The plug of this needle-tap is cylindrical, 

 about three-eights of an inch in diameter, and is carried in a socket which 

 it fits rather loosely. It is made to turn in this socket by the action of the 

 reciprocating magnet, a couple of studs on which are brought into con- 

 tact with a small pin connected with the plug, and forming, in fact, the 

 handle of the stop-cock. The annular space between the j^lug and the 

 socket — which is about the one-thousandth part of an inch — is filled with 

 oil, which is retained by capillary attraction between the two surfaces, the 

 joint being thus rendered perfectly gas-tight. The oil of bitter almond is 

 used on account of its non-oxydizable character, and from the power it pos- 

 sesses of resisting the action of very low temperature. Such is the appa- 

 ratus designed by Mr. Fox, in which it will be seen that a very special fea- 

 ture is the introduction of a fixed core which can be magnetized so as to< 

 render its poles reversible at pleasure, and, in conjunction with it, a move- 

 able magnet, the polarity of which, however, is permanent. 



We have now described the means whereby this apparatus is rendered; 

 active and the method of operating with it as witnessed by us on our visit 

 to the Fulham station. Assuming a group or series of gas-lamps to be- 

 connected by a conducting wire, the ends of the wire from this circuit are 

 connected with a switch, which is simply a little piece of mechanism for 

 placing the circuit in communication with, or disconnecting it from the 

 battery. An electric current is first sent through the circuit from an ordi- 

 narily powerful telegraph battery. The result is that the soft iron core in 

 each apparatus becomes converted into a temporary magnet, and the per- 

 manent reciprocating magnet above it is made to turn upon its axis. In 

 performing a partial revolution the projections upon it engage with the pin 

 or handle of the stop-cock, and, turning that around, open the cock and 

 admit the gas to the burner. The battery is then disconnected from the 

 circuit, and a condenser is charged by means of a Eumkorff coil, and then 

 discharged through the circuit. The result is that an independent electric 

 discharge is induced at the burner of every lamp at the same moment, and 

 the gas is ignited by means of a pair of metallic points, which are con- 

 nected with the secondary coil, and which deliver the spark. To extin- 

 guish the light the wires are reconnected with the battery by the means of 

 a switch, but in such a manner as that a reverse current is obtained. The 



