EQUIPMENT. 29 
of work, and finally in expense, have made deep-sea dredging a 
possibility on comparatively small vessels. It would have been 
difficult, if not impossible, on a small vessel of the. size of the 
“Blake” (of only three hundred and fifty tons burthen) to 
make provision for the equipment of hemp rope necessary for 
a season of dredging at the depths in which we usually worked 
in the Gulf of Mexico. Our stock of steel rope was only six 
thousand fathoms. The loss of rope was trifling, and much of 
the original steel rope, after three years of constant use dur- 
ing two previous cruises, was still available during the third 
cruise, 
The wire rope we used was of galvanized steel with a hemp 
core; it measured one and one eighth inches in circumference, 
weighing one pound to the fathom, with a breaking strain of 
over eighty-six hundred pounds, as tested by the Roebling & 
Sons’ Company, the manufacturers. We took with us only two 
coils, each of three thousand fathoms. One coil was on deck, 
wound to an iron reel and frame provided with a friction-brake 
for lowering the dredge or trawl, the whole space occupied by 
this length of rope on the reel being only five feet long, four 
feet wide, and five feet high. In addition to the economy of 
space thus gained, we were enabled to dispense with sending 
down heavy weights to drag in front of the dredge at a dis- 
tance from the frame, as was invariably done by the “ Chal- 
lenger," the weight of the steel rope in water rendering this 
unnecessary. Our greatest gain from the use of steel-wire rope 
came from the rapidity with which we could lower and hoist 
the dredge. In fact, this was done as rapidly as is customary 
in lowering or hoisting skips on the slope of a mine. Our 
usual speed d in lowering the dredge, until it came within a few 
fathoms of the bottom, was between two and a half and three 
minutes for a hundred fathoms, when we lowered more care- 
fully, and then payed out the slack very gradually, the dredge 
dragging on the bottom all the time. In bringing it up after 
the dredge was clear of the bottom, we hoisted again at the 
same speed, and as far as I could perceive the specimens were 
none the worse for their rapid upward journey. This gave us 
a chance to make several hauls a day, and by not leaving the 
