he roof for each chimney or other
projection. But as the lightning is liable to melt the plate at the
point where it enters, especially if the metal be tin or zinc, it is
well to solder points at the angles. Some, "to make assurance doubly
sure," carry the rods over the whole distance quite to the ground in
addition. All authorities consider such a system as this to be as
complete a defence against lightning as possible.

"If," says Harris, "a building or a ship were perfectly metallic in all
its parts, no damage could possibly arise to it when struck by
lightning, since the explosive action would vanish the instant the
electrical agency entered the metal. In applying lightning-conductors,
therefore, as a means of guarding against the destructive effects of
lightning, our object should be to carry out this principle in all its
generality, and bring the building or ship as nearly as possible into
that state of passive electrical resistance it would have supposing the
whole mass were iron throughout."

After the most careful and extended inquiry possible to him, it is the
writer's conclusion that in nearly every case of serious damage by
lightning to a building having conductors of any well-known system
(except the horizontal, which is not a conductor at all in the usual
sense of the word), the failure to protect has been on account of a
_defective ground-connection_. The fact is the more surprising as this
connection is so much within control and is the least costly part of the
system. This fault has arisen from the failure of lightning-rod men, as
well as owners of buildings, to apprehend what constitutes a
ground-connection for electricity. If the eye sees the end of the
conductor pass a short distance beneath the surface, all the connection
necessary is thought to be effected, because "the ground is always wet
enough in a shower." In the cities it is customary to connect the rod
with the water-or gas-pipes in the street, which makes the conduction
perfect. In the absence of these it is best to carry the rod to a well;
and it is always desirable to enlarge the lower end of the conductor,
which may be done by soldering it there to a sheet of copper. If the
termination of the line cannot be carried to a well, it should be
deeply buried in a bed of coke or charcoal that has been subjected to a
red heat.

A season or two ago a large barn in the vicinity of Boston was struck by
lightning, and though there were rods at th