METALLIC WIRES BY ELECTRICITY. 469 
mediately following it; and further, this progression must take 
place equably, so that in every part of the wire the same num- 
ber of sections become electrified in the same interval of time. 
~The laws of the electrical excitation of heat support this view 
in the most distinct manner. We will call the discharge of the 
battery taking place in this manner the constant or continuous 
discharge. But suppose that at one molecule of the connecting 
wire the electrical state is in some manner prevented from com- 
municating itself to the next contiguous molecule, the continuous 
discharge can then no longer take place. That molecule will 
become much more strongly electrified than it would have been 
by the continuous discharge, and its electricity will continue to 
increase in intensity until it is enabled to overcome the obstruc- 
tion offered to it, and thus bring itself into equilibrium with the 
electricity of another molecule. The molecules thus being 
brought into electrical equilibrium are no longer in intimate 
contact, but are at a measurable distance from each other. Thus 
a totally different mode of discharge is here concerned, from that 
which we previously examined. It is no longer imperatively 
necessary that all the particles of a normal section of the wire 
should be in the same electrical state at the same time ; the direc- 
tion of the discharge is no longer necessarily in the same line 
with the axis of the wire, but may form any angle with it. As 
also a certain time elapses before the first particle acquires suffi- 
cient electric tension, and during that time the progression of 
the discharge is retarded, therefore the discharge will not be 
propagated in the same space of time through wires of equal 
length. It may happen, that whilst in one part of the wire this 
propagation of the discharge by starts or jerks is taking place, 
in another part continuous propagation may be going on; but 
the discharge of the battery can then no longer be completed 
in a constant manner, and we must designate this mode as the 
intermittent or discontinuous discharge. The effects which a 
discontinuous discharge exerts upon a connecting wire may be 
deduced from known experiments, in which this mode of dis- 
charge by a discontinuous connexion of the battery was arti- 
ficially effected. Phznomena of light, fusion and mechanical 
action occur. A chain of links, through which discharge was 
made, became luminous, metallic powder was evolved from it, 
the links were forced from their positions, and some of them 
melted together. A string of metallic beads was torn in pieces 
