her company bought about an equal
amount of the same kind of cable, and in a comparatively short time the
current had to be shut off the lines and the whole installation repaired
and parts of it replaced. Both of these experiences have been repeated
many times and will be again, although it is simply a distinction
between a good cable properly laid and a good cable ruined by careless
and incompetent workmanship.

Every failure can be traced to poor work in the original installation or
to the use of a cheap cable, both causes being due, generally, to that
false economy which looks for too quick returns. A poorly insulated line
wire and a poorly insulated cable are two very different things.
However, it is a fact that by the use of a good cable it is not
difficult to construct an underground system for light, power, telegraph
or telephone uses that will be superior to overhead lines in its service
and in cost of maintenance. The ideal underground system must have as a
starting point a system of subways admitting of the easy drawing in and
out of cables and affording means of making subsidiary connections
readily and with the minimum of expense and interruption of service.
This is practically accomplished by a subway consisting of lines of pipe
terminating at convenient intervals, say at street intersections, in
manholes, for convenience in jointing and in running out house
connections. These pipes, or ducts, as they are called, should be for
two kinds of service; the lower or deeper laid lines for the main or
trunk circuits, and a second series of ducts laid nearer the surface,
running into service boxes placed near together for lines to "house to
house" connections. In some cities where it is allowed to run overhead
lines, the plan of running but one service connection in a block is
followed, all customers in the block being supplied from a line run over
the housetops or strung on the rear walls.

This makes unnecessary all subsidiary ducts except a short one from the
manhole to the nearest building in the block, and effects a considerable
saving in pipe, service boxes, cables and labor. The manholes should
have their walls built up of brick, the floors should be of concrete,
and there should be an inside lid which can be fastened down and the
manhole thus made water-tight.

For ducts wood, iron or cement lined pipe may be used. To preserve the
wood it is generally treated with creosote, which, in contact with the
lea