GEOLOGY. 265 



" The lead used was but lOlbs. weight, with a Stellwagen cone fitted 

 to it. Nothing else was attached to the wire, but a small instrument 

 (weighing about 61bs.) invented by yourself for indicating the depth 

 reached. I had tested this several times to considerable depths, and 

 found its indications correct. We had on board 11,300 fathoms of wire, 

 weighing 3,025lbs.. all of the best English steel, of five different sizes. 

 Every part was tested to bear at least one third more than the weight 

 which it was calculated to sustain. An extent of 7,000 fathoms of this, 

 weighing 1, 800 Ibs.. carefully measured and marked with small copper 

 labels, was linked into one piece and wound upon an iron cylinder 3 feet 

 in length and 20 inches in diameter, the largest-sized wire being wound 

 first, so as to be uppermost in sounding. Two swivels were placed 

 near the lead, and one at each thousand fathoms, to meet the danger 

 of twisting off by the probable rotary motion in reeling up. The 

 cylinder with the wire was fitted to a strong wooden frame, and ma- 

 chinery attached fly-wheel and pinions to give power in reeling 

 up. Four men at the cranks could reel up with ease, with the whole 

 weight of wire out. The whole apparatus could be taken apart and 

 stowed away in pieces. It being so large and massive, this was indis- 

 pensable in so small a vessel as the Taney. When wanted for use, 

 the frame was put together and secured to the deck ; the reel hoisted 

 up from below and shipped in its place ; a fairleader was secured to 

 the taffrail, being a thick oak plank, rigged out five feet over the stern, 

 having an iron pulley fitted in its outer end, and two sheet-iron fenders 

 of semicircular shape, fitted under it, to guard the wire from getting 

 a short nip in the drifting of the vessel. The wire was led aft, from 

 the reel over the pulley, which traversed freely in the fairleader, and 

 passed between these fenders into the water." 



The investigations upon the under-currents were few in number, and 

 none were made in the Gulf Stream, but enough was done " to war- 

 rant the conclusion that the under-currents are generally stronger, set- 

 ting in various different directions, than those of the surface." The 

 following was the mode practised for testing the under-currents. "The 

 surface-current was first tried by the usual mode (a heavy iron bottle 

 being lowered from a boat to the depth of 80 fathoms) ; then, for the 

 trial of the under-current, a large chip-log, of the usual quadrantal 

 form, the arc of it measuring full four feet, and heavily loaded with 

 lead, to make it sink and keep upright, was lowered by a light but 

 strong line, to the depth of 126 fathoms ; a barrega was attached as a 

 float, a log-line fastened to this barrega, and the rate of motion of this 

 float, as measured by this log-line and the glass, and the direction as 

 shown by a compass, were assumed as the velocity and set of the un- 

 der-current. No allowance was made for the drag of the barrega, 

 which was always in a different direction from the surface-current." 



The temperature of the water at various depths was also a matter 

 of investigation, and the following are some of the results. May 12, 

 water at surface, 75 ; at 50 fathoms, 76 ; at 100 fathoms, G9 3 . May 

 13, at surface, 77.5; 50 fathoms, 76.5; 100 fathoms, 74.5; 500 

 fathoms, 53. May 14, surface, 77 ; 1,050 fathoms, 49 3 . May 18, 

 surface, 70; 100 fathoms, 65. In crossing the Gulf Stream, at 8 



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