This grapnel was successfully
used on the Anglo-American Telegraph Company's repairing steamer Minia
in the summer of 1881.
Subsequently, in discussing the construction of the grapnel with
Captain Troot, we concluded that something was yet wanted to render
the successful working in deep water absolutely sure, and we decided,
consequently, to make certain alterations.
This improved form may be constructed, either with a contact-plate in
each prong, or with one contact-plate common to all the prongs; the
latter is somewhat simpler, and is therefore the plan that we usually
adopt. Both forms are shown in the accompanying diagrams. The form
of grapnel in Diagram No. 1 has one advantage over the other in this
respect, viz., that should a prong be ruptured so as to render it
useless, the fact would immediately be known on board. A circuit formed
in such a manner, by the breaking off of a branch lead, would have
greater resistance than that formed by the contact resulting from
pressure of cable on the plungers; this difference would be manifested
on the indicator (of low resistance) placed in circuit with the
alarm-bell, or, if any doubt remained, a Wheatstone's bridge, or simpler
still, a telephone might be made use of.
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