610 
ME. J. PRESTWICH ON SUBMARINE TEMPERATURES. 
series of observations made in the North and South Atlantic, at a uniform depth of 
360 feet, the importance of which consists in showing, as Horner and Kotzebue had 
previously done, that near the equator the water at and beneath the surface is colder 
than a few degrees further north and south. Six’s self-registering thermometers were 
used. No protection mentioned. 
Dr. Wallich* gives, in 1862, one temperature-observation at a depth of 600 feet, 
on the well-known occasion of the deep-sea soundings between England and America. 
Between 1860 and 1868 the several other expeditions undertaken to obtain deep-sea 
soundings in different parts of the world for telegraphic purposes afforded favourable 
opportunities for temperature-observations. Such were those obtained in 1868 by Capt. 
SHORTLANDf between Bombay and Aden, which are recorded in a series of means. They 
extend in one case to the depth of 13,020 feet, and give a reading of 33°*5, and in 
another, more westward, to 7800 feet, with a reading of 36°. These readings have, I pre- 
sume, been corrected from the original observations. 
Again, in 1868 Commander Chimmo $ made a series of observations on the American 
side of the North Atlantic, at depths extending to 12,000 feet, and recording tempe- 
ratures of 42°. It is merely stated that the experiments were made with “new and 
delicate thermometers,” which were without protection, and the readings are un- 
corrected. 
In August 1868 the 4 Lightning ’ sailed on the first of that series of deep-sea researches 
which, conducted under the combined superintendence of Dr. Carpenter and Professor 
Wyville Thomson, with the addition afterwards of Mr. Gwyn Jeffreys, and followed 
up systematically in subsequent voyages, have already yielded sudi valuable and impor- 
tant information on the natural history and physics of the depths of the sea. 
Regarding the relative merits of the several methods employed by the early observers, 
a few words may be said. The water-bucket, when properly constructed, of sufficient 
size, and when well handled, was not badly contrived to determine the temperature at 
moderate depths. It was free from the errors of pressure and index to which thermo- 
meters are liable. The errors depend upon the size of the apparatus, the proper 
closing of the valves, the rapidity of hauling in, and the difference of temperature 
between the bottom- and surface-waters. When the latter is not great the error can 
be but small ; and such is the case in those Arctic seas where it has been chiefly used. 
As so considerable a number of observations were made with this apparatus by Scoresby 
and Franklin, it might be desirable to determine by experiment the amount of correction 
required to adjust the error of this particular apparatus. 
In the case of Lenz’s bathometer, he made a series of experiments to determine 
* The North- Atlantic Sea-Bed, 1862, p. 145. 
t Admiral Sherabd Osborx, “ On the Geography of the Bed of the Atlantic and Indian Oceans and Medi- 
terranean Sea,” Journ. Roy. Geogr. Soc. 1871, vol. xli. p. 58. 
I Proc. Roy. Geogr. Soc. 1869, vol. xiii. p. 92. 
