264 ANNUAL OF SCIENTIFIC DISCOVERY. 



of land which skirt our coast, have been thrown up, and even Long 

 Island itself has probably been formed in the same way. 



OBSERVATIONS UPON THE DEPTH, CURRENTS, TEMPERATURE, 

 AND TRANSPARENCY OF THE OCEAN, EXTENT OF THE GULF 

 STREAM, ETC. 



THE maximum depth of the ocean has never yet been ascertained, 

 and never can be by the ordinary mode of sounding-. Capt. Ross 

 adopted a method of obtaining- deep-sea soundings by throwing- over a 

 heavy weight to which a small line was atttached. By this means he 

 succeeded in penetrating 4,600 fathoms (about 27,000 feet), when the 

 weight broke off without reaching- the bottom. Bottom has, however, 

 been obtained frequently at two and three thousand fathoms. Experi- 

 ments show that the great valleys of the ocean run at right angles to 

 the ranges near our coast. The basins of the southern hemisphere 

 dip and rise alternately from the equator towards the pole, causing 

 very unequal depths of water. 



Experiments made by Capt. Wilkes indicate that light penetrates 

 the ocean to the depth of 80 fathoms (480 feet). The depth at which 

 objects cease to be visible to the eye is much less. A pot painted 

 white was let down into the water and the point of invisibility marked ; 

 upon taking it out the point of visibility was marked, and the two 

 were found to vary but a fathom or two. In water at 36 F. the pot 

 disappeared at six fathoms; in water at 76 F., at thirty fathoms; in 

 the Gulf Stream, at twenty-seven fathoms ; just outside of it, at twenty- 

 three fathoms. 



A report made to Lieut. Maury by Lieut. J. C. Walsh, of some 

 observations on the Gulf Stream made in the schooner Taney, contains 

 many interesting facts. He says, "Though we did so much less 

 in deep soundings in the Atlantic than expected, owing to the rough 

 weather, bad state of the vessel, and loss of so much wire in the first 

 experiment, nevertheless, the proving the ocean to have a depth of 

 more than 5,700 fathoms (34,200 feet, or more than six statute miles), 

 as was satisfactorily done in this first trial, is alone of much interest 

 and importance. This vast depth, greater than the elevation of any 

 mountain above the surface, and the greatest depth of the ocean ever 

 yet measured, was reached without finding bottom, in latitude 31 59' 

 north, longitude 58 43' west, on November 15th, 1849. The wire 

 broke at this length, 5,700 fathoms, at the reel, and this large portion 

 of our supply was thus so early lost. It preserved the exact plumb 

 line throughout the sounding ; there was a steady, uniform increase of 

 weight and tension, with no check whatever during any instant of its 

 descent, which proves that it could not have touched the bottom before 

 the break. It had been very carefully measured and marked, so that 

 the fact that the ocean here is deeper than 5,700 fathoms can be relied 

 upon as accurate. The time occupied in the descent of the 5,700 

 fathoms, at the moderate rate it was allowed to go off the reel, was 

 one hour and a half." 



The mode adopted in the deep-sea soundings is thus described: 



