DESCRIPTION OF THE EXPEDITION. gti 
fitted with fore and aft sails. She had already auxiliary steam, with a two-bladed 
propeller. Her tonnage is 900 tons and coal-capacity 95 tons in the bunkers and, on 
emergency, 30 tons on deck. Her economical consumption is 9 tons per diem at 
8 knots, this giving her a steaming-range under very favourable conditions of about 
2500 miles. Of her sailing-capacity we had little experience, winds being generally 
contrary. She had a high forecastle, bridge forward, a deep waist, and a high poop. 
Unfortunately there was really no accommodation beyond what was required for her own 
officers and crew. Her deck-space was limited, but the poop was most generously given 
up to us as far as possible for our gear. Her boats consisted of two steamboats, two 
whaleboats, two skiffs, and a dinghy. Her complement was 100 officers and crew (PI. 2). 
We were singularly fortunate in that the Sealark was entirely officered from the 
Surveying Branch of the Navy, so that we were able to resign all topographical, 
meteorological, and indeed most oceanographical work of a physical character into other 
hands. She was under the command of Comm. Boyle T. Somerville—a most skilful 
hydrographer and a most charming man,—who took the keenest interest throughout 
and who assisted in every part of the work. In particular, he took all the observations 
for magnetic variation, and undertook the examination of the bottom-samples as they 
came up, a proceeding necessary for getting indications of shallow banks in the vicinity. 
To his unfailing interest, courtesy, and kindness any geographical success that the 
Expedition may have met with must be largely ascribed, as must all the pleasant 
relations which throughout existed on board. ‘The other officers of the ship were 
Lieut. Lay (Navigator and Senior Surveyor), Lieut. Hancock (1st Lieutenant), Lieut. 
Craven, Mr. Alexander (Boatswain on Special Service and 2nd Class Surveyor), Mr. Beer 
(Engineer), Mr. Evans (Boatswain), Paymaster Bainbrigge T. Fletcher, and the late 
Surgeon Simpson, each of whom most cheerfully assisted us in every way in his power. 
Detailed description of the equipment of a vessel for such work as we were under- 
taking is unnecessary. For sounding there were on either side of the forecastle Lucas 
machines, each holding 5000 fathoms of wire. The position was an especially good one, 
because the officer on duty could watch the sounding and communicate with the engine- 
room when necessary. Each machine was provided with a large driving-wheel, which 
could be instantaneously connected to the winch, situated at the base of the mainmast, 
by leads attached to the rigging, A Lucas machine consists of a large drum carrying 
piano-wire, with a flattened rim to which brakes can be instantaneously applied. From 
this the wire is led over a guiding-wheel of known circumference (generally half a 
fathom), which is carefully adjusted so as to revolve absolutely freely. On one side of 
the frame which supports this is an indicator, on which the number of fathoms can be 
read off as the wire runs out. The movements of the ship when sounding are remarkably 
simple, being only such as are required to keep the wire vertical, the ship being laid at 
starting with the wind about one point off the starboard or port bow in accordance with 
which machine is being used. The machine is very accurate, and each sounding is toa 
certain degree checked, since, in “ heaving in,” the indicator registers the backward 
revolutions of the wheel and should return to zero; if it does not, a fresh sounding is at 
once taken on the same spot. The rate at which the wire runs out depends upon the 
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