Tables of temperatures of the sea at different depths beneath the surface : reduced and collated from the various observations made between the years 1749 and 1868, discussed / by Joseph Prestwich.

  • Prestwich, Joseph, 1812-1896.
Date:
1875
Catalogue details

Licence: Public Domain Mark

Credit: Tables of temperatures of the sea at different depths beneath the surface : reduced and collated from the various observations made between the years 1749 and 1868, discussed / by Joseph Prestwich. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    5/98 (page 589)
    Fahrenheit, and Centigrade, and the depths are recorded in feet, fathoms, the ‘old French foot,’ ‘toise’v, ‘ brasse,’ ‘metre,’ and the ‘ yaden,’ while the longitude is some- times that of Greenwich, at others that of Paris. I have reduced these various measures to a common scale, adopting for temperatures that of Fahrenheit ; for length, the English foot; and for longitude, the meridian of Greenwich. As in these reductions some errors may have crept in, references are given to all the original readings. In the Lists of Observations (pp. 639-70) the degrees of temperature at depths stand as they are recorded by the several observers, without the correction adopted for the Sections. The place of each observation is laid down on a recent Admiralty Chart of the world (Plate 65), in accordance with the longitude and latitude given by each observer, without any attempt at correction, which, in some of the early observations may possibly be necessary. The observations thus reduced are tabulated in three groups. Table I. gives the deep-sea temperatures m the Northern Hemisphere from the Equator to the Polar Circle, and in the same way Table II. gives those in the Southern Hemisphere. The observa- tions in inland seas are given in a separate Table, No. III. A list of temperature-soundings, made up to date, was given by Peron in 1816. It was limited to 4 of his own, and to 16 of Forster’s and iRviNG’sf. In 1832 D’Urville $ gave a greatly extended list, embracing as many as 421 observations, which he arranged according to zones of depth ; and in 1837 Gehler § published a list of 226 observations arranged according to latitude. These, I believe, constitute all the general lists that have been published. The number of observations recorded in the present Tables amount to 1356. In the following pages I have givenfirst, a notice of the many voyages on which soundings for deep-sea temperatures were taken, with an account, when possible, of the mode m which the observations were made; secondly, a summary of the opinions founded on these data; and thirdly, a statement of the results obtained and of the conclusions to be formed thereon. Besides the error due to pressure, which, as so many of the older soundings were made at small depths, is frequently unimportant, there is that arising from the angle of the line from the vertical caused by currents, and another due to the tension of the rope by strain and wet, which is sometimes not inconsiderable. I have, however, in drawing the sections, given the depths without correction for these causes, so as to place all the observations on the same footing, as it is but rarely, although there are exceptions, that these particular sources of error were noticed or mentioned |]. * Ttie Eoot= 12-79 inches; the Toise=76-68 inches; the Brasse=63-93 inches, t Voyage de decouverte aux Terres Australes, vol. ii. p. 327. t Voyage de 1’Astrolabe, vol. x. Chap. III. Physique. § Gmuit’s Physikalisches AVbrterbuch. Sechster Band, Dritte Abtheilung, Mc-Mj, pp. 1676-82 II The older deep-sea soundings have been found to be liable to serious error, arising from the difficulty in actual fixing the depth of sounding; hut in these Tables there are few of that depth to involve this particular error; still some of the deeper ones must be looked upon with doubt. 4 K 2