38 
POPULAR SCIENCE REVIEW. 
that of a four-horse engine — would be required for one machine, 
so that the cost of production would be thus reduced These 
calculations are, of course, irrespective of first cost of plant and 
machinery and of interest on capital ; but they serve to show 
approximately the working cost of this light. 
Another worker in the field of electrical science, who is at 
present pursuing his investigations with a view to demonstrating 
the indefinite division of the electric current is M. Antoine 
Arnaud, his patents not being yet quite completed. M. Arnaud 
appears to have succeeded in dividing and controlling the cur- 
rent, so far as experiments on a small scale are concerned. He 
has shown that a large number of lights can be maintained in 
one circuit, and that the extinction of any of the intervening lamps 
had no effect upon the remainder. M. Arnaud expects to be 
able to light a thoroughfare with a number of lamps, giving an 
uniform light throughout, and without fear of the extinction of 
one or more affecting the rest. Mr. Wilde, whose name is 
already honourably known in connexion with electro-dynamic 
machines, has introduced an ingenious simplification of the 
Jablochkoff candle, which dispenses with the intervening kaolin 
or plaster diaphragm. In a paper read before the Manchester 
Literary and Philosophical Society he had already pointed out 
the fact that when the electric light is produced from the ends 
of two carbon pencils placed parallel to each other the carbons 
will burn steadily downwards from the top until they are wholly 
consumed, without any insulating material between them. It 
was observed that even when the circuit was completed at the 
bottom of a pair of carbons close to the holders the arc im- 
mediately ascended to the points and remained there. This 
occurred in whatever position the carbons were placed. Two rods 
are therefore placed side by side, one being fixed, the other 
hinged at the base, and pressed gently against it by a spring. 
Directly the current passes the spring is overpowered by an 
electro-magnet in circuit, which separates the movable rod to 
the proper distance from its fellow. The need for a u priming ” 
to start the arc is thus simply superseded. 
DESCRIPTION OF PLATE II. 
Chapman's Electric Lamp. Specification dated a.d. 1855, April 3, No. 739. 
A. Gravity holder for upper carbon, controlled by 
B. Brak ewheel and brake ; the latter being actuated by 
C. An electro-magnet, on closing the circuit. 
D. Second electro-magnet, causing a separation between the carbons, and 
establishing the arc. 
E E. Terminals to battery. 
