CHAP. I. ] THE EQUIPMENT OF THE SHIP. 71 
necting shaft and screw. At full speed the engines travel at 
about 240 revolutions a minute; and on the trial for speed over 
the measured mile the boat averaged eight knots an hour. The 
dredging-engines are fitted to the top of the boiler; they are a 
direct-acting horizontal pair, the cylinders at the after-end of the 
boiler, and the crank-shaft forward. The shaft extends beyond 
the boiler on both sides, and at each end a drum is fixed. The 
drums are constructed with two sheaves, and it is to the greater 
or the lesser of these that the dredging-line is led. 
It is impossible, in the limited space at present at my dis- 
posal, to do more than sketch the more prominent of our equip- 
ments and methods; but even now, after nearly a year’s expe- 
rience, I feel justified in expressing my opinion that the ar- 
rangements for scientific work on board leave very little to be 
desired. 
The Challenger was ready for sea early in December, 1872, 
and, before she left Sheerness, some of the Lords of the Admi- 
ralty and the committee of the Royal Society visited the ship. 
A party of sixty sat down in the handsome ward-room where 
we now have our general mess, and good wishes and hopeful 
anticipations were warmly exchanged. We shall not soon for- 
get the hearty British cheer of encouragement which rang out 
from a chorus of the voices which most influence the destinies 
of their country and their time, as our illustrious guests bid 
farewell to the Challenger from the deck of the steamer which 
was to take them to the shore. 
Thus, with every possible advantage, and in the highest hope 
of being able to fulfill her difficult mission, the Challenger cast 
off from the jetty at Portsmouth at 11.30 a.m. on Saturday, the 
21st of December, 1872. Leaving England with the drum up, 
in the middie of an unusually trying winter, it was not to be 
expected that we should escape without roughing it a little. 
This we certainly did for a week or so in the mouth of the 
Channel and the Bay of Biscay, and with this good result, that 
