Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/79

 Temperatures of the Pacific.

Latitude.

Longitude (corrected to Greenwich).

Depth.

Temperature. Surface. Bottom.

Observer & Date.

ft.

51 34 N. 161 41 E. 5741 53.2 36.6 Tessan 1832

28 52 N. 173 9 E. 3600 78.0 41.0 Beechy 1828

18 5 N. 174 10 E. 4261 76.6 40.8 1836 81.0

4 32 N. 134 24 W. 12271 35.2 The 'Bonite'

Equator (near) 179 34 W. 6000 1837 86.0 36.6 Kotzebue 21 14 S. 196 1 W. 5500 1824 81.0 36.0 Lenz

32 57 S. 176 42 E. 4692 1834 61.4 41.8

43 47 S. 80 6 W. 6400 55.6 36.2 Tessan 1841 These observations tend to show that in the greatest depths, both of the Atlantic and Pacific Oceans, the temperature is not higher than from about 36° to 40° ; and allowing for correction of the instruments, the actual temperature will probably be found to be in many cases 2° or 3° or more below this. A more systematic mode of proceeding, however, is needed ; for though the general rule may be considered to be established, local variations and exact measurements have to be ascertained. Notwithstanding, less attention has been paid to the subject of late years than formerly. Dr. Carpenter has now taken up the investigation, and has during the last three years carried out a series of observations in the North Atlantic which must prove of high value. Every care has been taken to guard against error ; and we shall soon no doubt have tables of temperature at all depths in this part of the ocean, which it is to be hoped will, concomitantly with the dredging-operations, be extended over the whole of the oceanic area.

Time will not allow me to enter upon the question of the course and cause of the cold under-stratum of the great oceans. As before observed it has been generally referred to undercurrents from the poles ; and later observations tend to confirm this ; but whether in the mid- Atlantic the flow is from the north or the south pole remains to be decided by more accurate inquiries. My own opinion inclines to an undercurrent from the North Pole. The occurrence of boreal and Scandinavian forms of life far south in the Atlantic favours this view. Whatever the cause, the fact of cold under- currents, which must have a powerful effect in bringing northern and southern forms into close vertical juxtaposition, is indisputable. All seas open to the Arctic and Antarctic oceans are doubtless subject to these conditions of warm surface-currents from the equator and cold undercurrents from the poles. In seas where there is no direct