Charles Gratton Page. ll 
of the writer’s recollection, must have been not far from fifteen 
inches, But the coil was composed of a large number of very 
short sections, of an axial length or thickness of something 
like perhaps three inchés each, made separately and joined end 
to end, with a flat metallic contact piece connected to each join- 
ing, for contact with one pole or the other of the battery. The 
several contact pieces formed together a continuous plane sur- 
face from end to end of the entire coil, with the exception of 
spaces between them sufficient to secure them from contact 
with each other. Over these contact pieces travelled the poles 
of the battery, taking their motion direct from the iron bar, 
the one pole near the lower, or advancing end of the bar, and 
the other pole above or in the rear (this was the arrangement 
in effect, though in this one machine there was a separate line 
of contact pieces for each pole), so as to include between them 
and take simultaneously into the battery circuit a number of 
short sections of the coil around the advancing end of the 
ar. In this way, during the downward stroke, a single short 
section at a time would be taken into the circuit in advance, 
and a single short section at a time dropped off in rear. So 
which, if the recollection of the writer is correct, the upwar 
stroke was not used. Even in the engines which succeeded 
this, and in which the magnetism of the bar was kept up by 
using both strokes, the transfer of the current from one end 
of the bar to the other was not effected without a still re- 
