The sun. [volume] (New York [N.Y.]) 1833-1916, 1915-01-09
SAFETY IN THE SUBWAY.
Suggestions for Impro,ing Conditions on
the Underground Rails.

To THE EDITOR OF THE SUN--Sir: II
Is not necessary to assume that an cleo
trical short circuit was the primary cause
OF Wednesdays subway nightmare. So to
do may lead public attention away from
more preventable sources OF trouble, the
popular idea being that a short circuit Ia
a mysterious phenomenon, obscure In its
origin and uncomfortable in its manifes-
tations, much after the manner Of the
lightning fash.
The trouble happened In a splicing box.
In these the continuity OF the copper
cables carrying the heavy operating cur
rents for the car motors, &c. IL broken
by necessary joints These Joints are a
combination OF mechanical attachment
and solder the former giving necessary
strength and the latter insuring a proper
electrical connection.
This work Is usually very carefully
done, and the nature OF the connection,
similar to the wiped joint on a lead pipe,
giving II larger cross section at the
junction point than that possessed by the
cable itself, provides In most cases large
factor OF safety. But IT, as is sure to
happen at some time. the soldering. that
Is, the electrical connecting, In carelessly
done, a latent defect exists In that case.
singuarly potent for trouble. For OBJ
serve what may happen:
The splice Is made. wiped and tapped.
Good or bad. II looks the same. il Is
carrying a certain current. below the
cable capacity, and in quantity which the
splice. though defective. wall pass without
heating. SO all IL well at the time.
Later the load on the cable is Increased f,
that IL practically always the case with
feeders. certainly In the subway, where
the line load has come up so rapidly.
The cable has a known capacity which
the engineers will not permit to he ex-
ceeded. but our defective soldered joint
has by reason of its defect a higher re-
sistance than the cable and begins 10
heat. a cable may heat considerably
without serious results, but not 30 a sol
dered splice The solder melts on. still
further increasing the resistance, and I'M
mediately the mechanically attached ends
OF the cable get hotter. melt and blow,
arclng and producing In confined space
the temperature and effects OF an electric
furnace.
The other cables in the well are melted
through and multiply disastrous effects,
and everything within range OF the arc
ing cable terminals. rubber. metal and
oven stone and cement. IL vaporized
turned into gases, which are driven semi
explosively into any space available; In
the subject case the subway tunnel
Some remedies suggest themselves
Electrical welding instead OF soldered
Joints at all important points Is one. !
am aware OF technical objections to this
but they should mean little TO cor
poration with the responsibilities, reve-
nues and engineering resources OF the In
terborough. and the results are certain.
In the meantime n device might be in
stalled contiguous to the splices that
would alarm the nearest station In the
event of any undue rise in temperature
and permit proper measures being taken
IN time. II is possible TO ascertain
electrically the resistance OF any cable
Joint and this may sometimes he done
but have seen many, many joints made
and put into service without any such
precaution. and Its neglect IL too easy TO
make II reliable. ID. VI. GoErscHius.
LITTLE FERRY, ~ j.. January s.