provides all the lubrication required. The double brushes, placed at
the extremities of the car, enable it to bridge over the numerous
gaps, which necessarily interrupt the conductor to allow cart ways
into the fields and commons adjoining the shore. On the diagram the
car is shown passing one of these gaps: the front brush has broken
contact, but since the back brush is still touching the rail, the
current has not been broken. Before the back brush leaves the
conductor, the front brush will have again risen upon it, so that the
current is never interrupted. There are two or three gaps too broad to
be bridged in this way. In these cases the driver will break the
current before reaching the gap, the momentum of the car carrying it
the 10 or 12 yards it must travel without power.

The current is conveyed under the gaps by means of an insulated copper
cable carried in wrought-iron pipes, placed at a depth of 18 inches.
At the passing places, which are situated on inclines, the conductor
takes the inside, and the car ascending the hill also runs on the
inside, while the car descending the hill proceeds by gravity on the
outside lines.

From the brushes the current is taken to a commutator worked by a
lever, which switches resistance frames placed under the car, in or
out, as may be desired. The same lever alters the position of the
brushes on the commutator of the dynamo machine, reversing the
direction of rotation, in the manner shown by the electrical hoist.
The current is not, as it were, turned full on suddenly, but passes
through the resistances, which are afterward cut out in part or
altogether, according as the driver desires to run at part speed or
full speed.