30 THREE CRUISES OF THE “ BLAKE.” 
dredge or trawl to drag too long on the bottom we obviated 
the great loss of time due to fouling, reversing, or any other 
accident out of sight. In the “Challenger” the best part of 
the day was generally consumed in making a haul at a depth 
of fifteen hundred fathoms. We experienced no inconvenience 
from the kinking of the rope, if it was kept well stretched, 
and not allowed to lie slack on the bottom. The uniform suc- 
cess attending the use of this rope during our dredging seasons 
enables me to recommend it to any future deep-sea dredging 
expedition, as insuring an economy of space, time, and money ; 
for the rope occupied about one ninth of the space required 
by a hemp rope, and was, at the end of the cruise, as good as 
when we first left Key West. 
Not the least superiority of the steel rope over the hemp 
rope is its power of telephoning, as it were, from the bottom. 
By keeping hold of the wire rope. on deck, the least movement 
of the dredge or trawl on the bottom is transmitted with ab- 
solute certainty, and it soon becomes an easy matter for the 
officer in charge of the dredging not only to tell whether the 
trawl is dragging well, but also the kind of bottom over which 
it is passing. The vibrations of the rope when the trawl passes 
over a gravelly, or a sandy, or a smooth, muddy bottom are all 
characteristic and in strong contrast with those produced by the 
quick jumps of the trawl over a rough and slightly rocky bot- 
tom. The movements of the dredge are repeated by the vibra- 
tions of the steel rope so promptly that the moment it pulls or 
passes over rough bottom the speed of the vessel can at once 
be checked, or its direction altered, before the tension is great 
enough to affect the accumulator. 
Heavy strains on the line can be detected in the same man- 
ner, and for greater safety an accumulator is connected with 
the pulley over which the wire rope leads to the bow of the 
vessel at the end of the dredging-boom. This accumulator (Fig. 
28) is made up of a series of india-rubber car-springs, suspended 
along the foremast and kept in place by iron guides. These 
are compressed by a strain, and expand again into their natural 
position when the pressure is taken off. The amount of com- 
pression indicates the care to be taken in handling the trawl 
