DEEP-SEA EXPLOKATION. 
351 
The actiou of the accumulator as a dynamometer is as follows: Tension on the 
dredge rope compresses the buffers, causing the scale bars to project beneath the 
yoke, when the degree of strain is read from the bars at their point of contact with its 
lower face. The marks are the same on both scale bars and on both sides of the bars, 
so that they can be read from forward or aft, or from either side of the deck. 
The hubs on the brass washers, which prevent the buffers from coming in contact 
with the tension rod, were devised by Lieut. Commander Sigsbee, U. S. N., on board 
of the United States Coast Survey steamer Blalce. Previous to their introduction the 
buffers were liable to grip the tension rod while they were compressed, making the 
apparatus sluggish in its action, a fault that no longer exists. It is, on the contrary, 
exceedingly prompt in expansion after being relieved of its load, and retains its 
elasticity under all conditions of service and temperature. 
The illustration shows 39 buffers mounted without compression; hence tlie 500- 
pound mark on the scale is some distance above the yoke; while in actual practice, 
with 44: buffers under comi)ression, it would be lowered nearly to it. 
STEEL-WIRE DREDGE ROPE. 
Steel-wire dredge rope was suggested by Prof. Alexander Agassiz, and first used 
on board the Coast Survey steamer Blalce in 1877, when its superiority over all other 
material was so conclusively demonstrated that it henceforth became the standard 
for deep-sea exi)loration. The Blalce'’s ro^ie was made by the John A. Eoebling’s 
Son’s Comi>any, Trenton, N. J. It was composed of 42 galvanized steel wires, Eo. 19 
American gauge, in 6 strands of 7 wires each, laid around a hemp heart. It was 
1.125 inch in circumference, weighed 1.14 pound per fathom in air, about 1 pound in 
sea water, and its ultimate strength was 8,750 pounds. A kink reduced its breaking 
strain to 4,500 pounds. 
Steel wire dredge rope was first used by the U. S. Fish Commission on board the 
Fish Rawlc in 1880. It was identical with the Blalce’’ s rope except that it had no hemp 
heart. 
The Albatrosses rope of 1882 was made by the Hazard Manufacturing Comi)any, 
Wilkesbarre, Pa. It was composed of 42 galvanized steel wires of the coinjiany’s 
special gauge, approximating to No. 18 American gauge, Avith G strands of 7 wires 
each, and had a hemp heart. It Avas 1.18 inch in circumference, Aveighed 1.32 pound 
per fathom in air, about 1.2 ijound in sea Avater, and its breaking strain Avas 12,850 
pounds. A kink reduced its strength about 50 per cent. It Avas made of the best 
crucible steel and developed great tensile strength, but it Avas stiff and unpliable, 
kinked badly, and usually broke without warning, like tempered steel. It aauis used, 
however, until 1886, when an effort Avas made to procure a more pliable rope Avithout 
sacrificing strength or materially increasing its size. 
A quantity of English rope Avas procured through the agency of J. W. Mason & 
Co., New York, which was made of the best English mild extra plow steel, composed 
of 42 galvanized steel wires. No. 18.1 B. W. G., ax)iAroximating to No. 17 American 
gauge, with 0 strands of 7 wires each, around a hemp heart. It is 1.184 inch in cir- 
cumference, weighs 1.31 i>ound per fathom in air, 1.09 ijound in sea Avater, and its 
breaking strain is 14,000 pounds. It is more pliable than crucible steel rope, less 
