CHAPTER. V. 
DEEP-SEA SOUNDING. 
The ordinary Sounding-lead for moderate Depths.—Liable to Error 
when employed in Deep Water.—Early Deep Soundings un- 
reliable-—Improved Methods of Sounding.—The Cup-lead.— 
Brooke’s Sounding Instrument.—-The ‘ Bull-dog’; Fitzgerald’s ; 
the ‘Hydra.’—Sounding from the ‘ Poreupine.—The Contour 
of the Bed of the North Atlantic. 
In all deep-sea investigations it is of course of the 
first importance to have a means of determining the 
depth to the last degree of accuracy, and this is not 
so easy a matter as might be at first supposed. 
Depth is almost invariably ascertained by some 
modification of the process of sounding. <A weight 
is attached to the end of a line graduated by attached 
slips of different coloured buntine (the woollen mate- 
rial of which flags are made, in which the colours are 
particularly bright and fast) into fathoms, tens of 
fathoms, and hundreds of fathoms; or, for deep-sea 
work, with white buntine at every 50, black leather 
at every 100, and red buntine at every 1,000 fathoms. 
The weight is run down as rapidly as possible, and 
the number of fathoms out when the lead touches 
the bottom gives a more or less close approximation 
to the depth. 
