Hydro-electric. adj.
(a) A current produced by a voltaic couple or the couple itself is
sometimes thus characterized or designated as a "hydro-electric current"
or a "hydro-electric couple." It distinguishes them from
thermo-electric.
(b) Armstrong's steam boiler electric machine (see Hydroelectric
Machine) is also termed a hydro-electric machine.
Hydro-electric Machine.
An apparatus for generating high potential difference by the escape of
steam through proper nozzles.
It consists of a boiler mounted on four glass legs or otherwise
insulated. An escape pipe terminates in a series of outlets so shaped as
to impede the escape of the steam by forcing it out of the direct
course. These jets are lined with hard wood. They are enclosed in or led
through a box which is filled with cold water.
Fig. 199. ARMSTRONG'S HYDRO-ELECTRIC MACHINE.
This is to partly condense the steam so as to get it into the vesicular
state, which is found essential to its action. Dry steam produces no
excitation. If the boiler is fired and the steam is permitted to escape
under the above conditions the vesicles presumably, or the "steam" is
found to be electrified. A collecting comb held against the jet becomes
charged and charges any connected surface.