184 Dr. Marcet on the specific gravity and temperature 
water was found to be 33 0 at the surface ; 30° at the depth of 
80 fathoms ; 29 0 at 200 fathoms ; 28.5° at 400, and 25 0 at 670 
fathoms.* These results are the more singular, as they are 
at direct variance with those obtained, nearly at the same 
period, by Lieut. Franklin, in the Polar or Greenland seas, 
in higher latitudes. It will be seen by the curious and va- 
luable table which Lieut. Franklin has permitted me to annex 
to this paper, that, with only one or two exceptions, he uni- 
formly found the sea to be sensibly warmer at great depths 
than near the surface, and that the difference often amounted 
to four or five degrees. Lieut. Beechy, one of the officers of 
the same vessel, and Mr. Fisher, who was on board the Do- 
rothea, both of whom made similar observations, have also fa- 
voured me with an account of their results, which, as will be 
seen by a reference to their respective tables, perfectly co- 
incide, in their general import, with those of Lieut. Franklin. 
* Captain Ross in his account of a ‘ Voyage to the Arctic regions/ has himself 
published some of the results which he obtained respecting the temperature of the 
sea in Davis’s Straits, and Baffin’s Bay. Thus in latitude 72,22, longitude 79, he 
found the temperature of ( the bottom of the sea, at the depth of 1050 fathoms, 28,5° 
(Appendix, p.lxxxv.). And in latitude 72,23, having examined the temperature of 
the sea at the depth of 500, 600, 700, 800 and 1000 fathoms, he found that it gra- 
dually decreased from 35 0 to 28! (Appendix, page cxxiv.). These differences, 
though not so considerable as that above related, all concur in establishing the ge- 
neral fact, that the lower strata, in that particular track of the northern ocean, are 
colder than the surface. The instrument which Captain Ross employed, was a regis- 
ter-thermometer, the indications of which were occasionally compared with the tempe- 
rature of the mud and earthy fragments of various kinds which he raised from the 
bottom of the sea, by an appropriate instrument of his own contrivance; as this mud, 
both from the quantity raised, and from the manner in which it was confined, retain- 
ed its temperature for a sufficient length of time not to be materially altered on reach- 
ing the surface. 
