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 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 



