THE TRIAL TRIP
Rehearsal of Cable Operations--Successful Experiments and Performances.
[Illustration: FIG. 22.--Deck of H.M.S. Agamemnon with Paying-out
Apparatus.]
The engineer-in-chief (Mr. Bright) arranged that this time an
experimental expedition should be first made, during which a complete
rehearsal was to be gone through of the various operations to be
performed during cable maneuvers. These operations were to consist of
making splices, picking up and buoying (besides laying) in deep water,
and exercising all hands in their work generally. It was on this
occasion also agreed that paying out should start from mid-ocean
instead of from either shore. It was further arranged that the main
cable should be buoyed at each end, and the connection to it by the
heavy cable from shore effected at the earliest opportunity.
[Illustration: FIG. 23.--Stowage of the Cable Coils on the Niagara.]
[Illustration: FIG. 24.--The Loading of the Agamemnon.]
All the 3,000 miles of cable was coiled into the two large ships by the
end of May. Fig. 22 gives a general idea of the paying-out apparatus
mounted on the deck of the Agamemnon, and Fig. 23 a view in section of
the fore-tanks of the Niagara when loaded with her cargo of cable. The
engineer had this time fitted cast-iron cones in the middle of each
cable-coil to meet the requirements of safe paying out, besides
providing a large margin of space to the hatchway above. Fig. 24 shows
the loading of the Agamemnon. The rest of the telegraph squadron was on
this occasion made up by H.M. Gorgon, H.M. paddle-steamer Valorous, and
H.M. surveying-steamer Porcupine.
The fleet set forth on their second cruise on May 29, 1858--this time
without any show of public enthusiasm. Mr. Bright was again assisted by
the same engineering staff, but Professor Thomson had agreed to take a
more active part in the electrical work. The Bay of Biscay was to be the
scene of the experiments--the actual site being about 120 miles
northwest of Corunna, where the Gorgon obtained soundings of 2,530
fathoms or nearly three statute miles.
The Agamemnon and Niagara were then backed close together, stern on, and
a strong hawser was passed between them. Each ship had on board some
defective cable for the experiments about to be conducted. The
proceedings may perhaps best be described by extracts from the
engineer's diary:
Monday, May 31st, 10 A.M., hove to, lat. 47° 11´, long. 9° 37´. Up
to midday engaged in making splice between experimental cable in
fore coil and that in main hold, besides other minor operations. In
afternoon getting hawser from Niagara and her portion of cable to
make joint and splice. 4 P.M., commenced splice; 5.15 splice
completed; 5.25, let go splice-frame (weight 3 cwt.) over gangway,
amidships, starboard side.[27] 5.30, after getting splice-frame
(containing the splice) clear of the ship and lowering it to the
bottom, each vessel (then about a quarter of a mile apart)
commenced paying out in opposite directions.
9 P.M., got on board Niagara's warp and her end of cable to make
another splice for second experiment.
June 1st.--1 A.M. (night), electrical continuity gone, the cable
having parted after two miles in all had been paid out.[28]
Since 1 A.M., engaged in hauling in our cable. Recovered all our
portion, and even managed to heave up the splice-frame (in perfect
condition), besides 100 fathoms of Niagara's cable, which she had
parted. Fastened splice to stern of vessel and ceased operations.
9.23 A.M., second experiment. Started paying-out again. Weather
very misty.
9.40, one mile paid out at strain 16 cwt.; angle of cable 16° with
the horizon: running out straight; rate of ship 2, cable 3.
9.45, changed to lower hold. 9.56, two miles out; last mile in
16-1/2 minutes; strain 17 to 20 cwt.; angle of cable 20°. 10.10,
last of the three miles out in 14 minutes.
10.32 A. M., four and a half miles out. Third experiment--stopped
ship, lowered guard, stoppered cable.
10.50, buoy let go, strain 16 cwt. when let go, the cable being
nearly up and down.
11.6, running at rate of 5-1/2 knots paying out, strain 21 to 23
cwt., varying. Cable shortly afterward parted through getting
jammed in the machinery.
The subsequent experiments were mainly in the direction of buoying,
picking up, and passing the cable from the stern to the bow sheave for
picking up. All of these operations were in turn successfully performed;
and finally, in paying out a speed of seven knots was attained without
difficulty. During all this time electrical communication had been
maintained between the ships; and it is somewhat remarkable that,
through this more or less damaged cable, the electricians were able to
work a needle-instrument and obtain a deflection on it of 70 degrees.
[Illustration: FIG. 25.--Experimental Maneuvers in the Bay of Biscay.]
And now, the program being exhausted, the ships returned to Plymouth. On
the whole, the trip had proved eminently satisfactory. The paying-out
machinery had worked well, the various engineering operations had been
successfully performed, and the electrical working through the whole
cable was perfect.