ME. J. PEESTWICH ON SUBMAEINE TEMPEEATUEES. 
589 
Fahrenheit, and Centigrade, and the depths are recorded in feet, fathoms, the ‘ old 
French foot,’ ‘toise’*, ‘brasse,’ 4 metre,’ and the 1 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 in 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’s f. 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 given : — first, a notice of the many voyages on which 
soundings for deep-sea temperatures were taken, with an account, when possible, of 
the mode in 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 || . 
* The Old Eoot= 12-79 inches; the Toise=76-68 inches ; the Brasse =63- 93 inches. 
t Yoyage de decouverte aux Terres Australes, vol. ii. p. 327. 
+ Yoyage de 1’ Astrolabe, vol. x. Chap. III. Physique. 
§ Gehler’s Physikalisches Worterbuch. Sechster Band, Dritte Abtheilung, Mc-Mj, pp. 1676-82. 
|| 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 ; but 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. 
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