of charging being merely to bring about the condition in which
part of the limestone can be consumed, the batteries themselves,
when in constant use, requiring to be renewed about once a month.
A handle at the box seat turns on any part of the attainable
current, for either going ahead or reversing, there being six or
eight degrees of speed for both directions, while the steering is
done with a small wheel.

"Light but powerful batteries and motors have also been fitted on
bicycles, which can act either as auxiliaries for hill-climbing
or in case of head wind, or they can propel the machine
altogether.

"Gradually the width of the streets became insufficient for the
traffic, although the elimination of horses and the consequent
increase in speed greatly augmented their carrying capacity,
until recently a new system came in. The whole width of the
avenues and streets in the business parts of the city, including
the former sidewalks, is given up to wheel traffic, an iron ridge
extending along the exact centre to compel vehicles to keep to
the right. Strips of nickel painted white, and showing a bright
phosphorescence at night, are let into the metal pavement flush
with the surface, and run parallel to this ridge at distances of
ten to fifteen feet, dividing each half of the avenue into four
or five sections, their width increasing as they approach the
middle. All trucks or drays moving at less than seven miles an
hour are obliged to keep in the section nearest the building
line, those running between seven and fifteen in the next,
fifteen to twenty-five in the third, twenty-five to thirty-five
in the fourth, and everything faster than that in the section