Cruise of School-ship "Mercury" in Tropical Atlantic Ocean. 1870-1871

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New York printing Company, 1871 - Atlantic Ocean - 33 pages
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Page 4 - Giraud, to obtain a series of soundings on the line of or near the equator, from the coast of Africa to the mouth of the Amazon, to observe the set of the surface currents and the temperature of the water at various depths.
Page 27 - Though the quantity of organic substance diminished as the stratum under examination was deeper, there still remained a visible amount in the water of four hundred or five hundred fathoms. It is probable, therefore, that even at the bottom of the ocean such organic substance may exist, not only in solution affording nutriment to animals inhabiting those dark abysses, as Professor Wyville Thompson has suggested, but also in the solid state.
Page 15 - The low temperature and great pressure of these deep strata, moreover, increase the solvent power of the water over gases, and this power is diminished as the cylinder is brought into the warmer strata above, and into the open air. Even the saline ingredients will suffer disturbance when they are held in solution by gases that will thus escape. For instance, this is the case with carbonate of lime.
Page 18 - ... tion for these variations must be determined in the case of each individual instrument, for the amount of this error will vary with the varying thickness of the glass, its form, and its power of resisting compression. In the experiments made by Dr. Miller on self-registering thermometers for deep sea sounding, published in the report of the Meteorological Committee of the Royal Society for 1869, it is shown that certain unprotected thermometers submitted to a pressure of two and one half tons...
Page 21 - ... in question. However this may be, it is doubtless through these deep troughs that much of the cold water of the North Polar current finds its way. In accordance with this, we perceive, on examining the temperature of the water, after the African verge of the greater or eastern sea trough is reached, that there is a difference in temperature between the surface and that at a depth of \ \ not more than two hundred fathoms, exceeding twenty-five degrees in many eases.
Page 25 - ... of the tropical Atlantic and Caribbean Sea a stratum of cold water, — cold, since its temperature is below 50. This is the conclusion to which Dr. Carpenter has come, as respects the Atlantic in higher north latitudes ; and in this important particular the cruise of the Mercury must be considered as offering confirmatory proofs of the correctness of the deductions drawn from the cruises of the Lightning and Porcupine.
Page 21 - From this point the mean depth across the ocean may be estimated at about 2,400 fathoms, but from this there are two striking departures — first a depression, the depth of which is 3,100 fathoms, and second, an elevation at which the soundings are only 1,900, — the general result of this...
Page 27 - A careful examination did not reveal the presence of any spectral lines, other than those belonging to the well-known elementary substances in sea-water. The specimens of the bottom, obtained by attaching to the soundingline quills or wooden tubes, I have transmitted to Dr. Carpenter, who has kindly consented to examine them. In a letter dated August 10, 1871, recently received, he says : "As far as I can see, they consist of the ordinary Atlantic mud, chalk in process of formation, with the ordinary...
Page 27 - In order to determine whether any hitherto-unknown element existed in these waters, I subjected the solid residue to examination with the spectroscope, volatilizing the substances by the aid of a voltaic current and induction coil. A careful examination did not reveal the presence of any spectral lines, other than those belonging to the well-known elementary substances in sea-water.
Page 9 - City of New York, on the chemical and physical facts collected from the deep sea researches made during the voyage of the nautical school ship " Mercury," undertaken by their order in the tropical Atlantic and Caribbean sea, 1870-1.

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