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75
Consequently a leakage current was continually passing to earth
from the negative at this place, and an equal current in the aggregate
from the positive side through many small leaks.
The lines of flow of current would be to absolute earth or zero
potential in all directions.
Any water pipes or gas pipes in the vicinity would be practically at
zero potential throughout on account of their metallic connection
with the whole mass of the water or gas mains of London. Consequently
the lines of flow of current would, to a large extent, converge on any
such pipes in the immediate vicinity, if only separated from the charged
conduit by damp earth.
In other words, there would necessarily be a flow of positive electricity
from such pipes to the surrounding earth, and thence to the
charged culvert.
But the flow of positive electricity from a metal into a damp
medium, or water, is always necessarily accompanied by the generation
of oxygen at the surface of the metal, which, if oxydisable, is thereby
corroded.
This is the action which has destroyed the water pipes.
The gas pipe happened to be laid in bitumen, and was thereby protected,
but the gas meter, touching a damp wall within the influence of
leakage, was affected.
The state of the system of St. James's and Pall Mall Electric Supply
Company, so far as it has been brought to my notice, may be briefly
summed up as follows:—
In September last two explosions occurred, due to accumulations of
gas and water respectively, a faulty pilot wire causing the explosion
of gas.
On 3rd November I held an inquiry into these explosions, and from
information given to me by the Engineer of the Company, I proposed a
test, which was carried out shortly afterwards, and revealed the existence
of a very serious earth connection on the negative main.
This earth connection the Company were unable to localise and
remove, and it continued in existence until the 5th inst., when it was
removed by disconnecting the section of main opposite Mr. Peat's in
Piccadilly. The local effect of this fault has been the damages now