338 Prof. Callan on the Induction Apparatus. 
is constantly diminished by the resistance of thewire. This 
electricity moving more slowly than when the coil and battery 
were connected, and in the same direction as the battery current, 
is not able to maintain in the core, or in the primary or second- 
ary coil, the magnetic power produced in them by the battery ; 
but it maintains a part of it, and prevents the core, the primary 
and secondary coil, from losing their magnetism in an instant, 
and consequently diminishes the intensity of the secondary cur- 
rent. The condenser prevents the gradual diminution of the 
velocity of the electricity flowing in the primary coil at the mo- 
ment its connexion with the battery is broken, and probably 
accelerates it; for in an instant after the battery connexion is 
broken, the end of the coil towards which the electricity is mo- 
ving, and the plate of the condenser connected with it, become 
positive. This positive plate instantly renders the other plate 
negative: the latter then attracts electricity to the former with 
an enormous force, on account of their very close proximity ; and 
if the plates of the condenser be of sufficient size, the electricity 
moving in the primary coil will be drawn with such force to the 
positive plate, that its velocity, instead of being diminished, will 
probably be increased. Thus the condenser removes the obstacle 
arising from the electrical state of the primary coil, to the 
sudden suspension of the magnetism of the core, and of the pri- 
mary and secondary coil, and probably increases their magnetic 
power by accelerating the current in the primary coil after its 
connexion with the battery is broken. The condenser not only 
removes an obstacle to the instantaneous suspension of the mag- 
netism of the core and of the primary and secondary coil, but it 
also supplies a force tending to destroy that magnetism ; for as 
soon as all the electricity moving in the primary coil is drawn 
to the positive plate of the condenser, it instantly rushes back to 
the negative one through the primary coil, and is drawn to itself 
by that plate with an immense force ; and in its passage through 
the primary coil, tends to reverse the magnetic poles of the core 
of the primary and secondary coil, and consequently to destroy 
their magnetism. Hence the effect of the condenser is to make 
the core, the primary and secondary coil, lose their magnetism 
instantaneously, and thus to increase the intensity of the second- 
ary current, or the length of the sparks produced by that current. 
This explanation of the action of the condenser is confirmed by 
the effect which I have found it to produce on the electrical cur- 
rents induced by the primary current in each section of the 
core, viz. an increase of their intensity. Now the only causes 
that can produce an increase of intensity in these currents are, 
an increase of the magnetism of the core, and of the rapidity with 
which it loses its magnetic power, or either of these two causes. 
