underground and in the station are frequent, with the natural result
that the operating of circuits underground is not there considered an
unqualified success. The writer has in mind two very different
experiences with underground cables. Several miles of cable were bought
by a certain company, carefully laid, and up to to-day not a single
burn-out or interruption of service can be attributed to failure of
cables; at about the same time another 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