170 



Messrs. Carpenter and Jeffreys on 



[Dec. 8, 



by a comparison of the diurnal averages of the surface-temperature of the 

 Mediterranean with those of the Atlantic, that the latter are at least four 

 or five degrees higher than the former, it may be fairly assumed that at 

 least half the increase was due to the passage from the colder Atlantic 

 water of the mid-channel into the warmer water of the Mediterranean 

 basin, the temperature of the latter being even here somewhat reduced by 

 the inflow of the former. — The 6o££o»z-temperature was found to be here 

 55° ; and this corresponded closely with that which we had met with in 

 the Strait (§ 32), while it was at least 5° higher than had been obtained at 

 corresponding depths on the Atlantic side. Being desirous of determining 

 the rate of its diminution, we took serial soundings at intervals of 

 10 fathoms down to 50, and then at 100 fathoms, with the following re- 

 markable result : — 



Surface . . . 

 10 fathoms 

 20 „ 



^ u >j 



50 „ 



100 „ 



586 „ (bottom) 



Thus there was a fall of 9°*5 in the first 20 fathoms, of 5 0, 3 in the next 

 30 fathoms, and of 4°*6 in the next 50 fathoms ; whilst from 100 fathoms 

 to the bottom at 586 fathoms there was no further descent. 



46. Whilst we were prosecuting these inquiries, we found ourselves 

 surrounded — the surface of the Sea being extremely calm — by great num- 

 bers of the beautiful floating Velellce,v}hich are occasional visitors to our own 

 Coast, accompanied by the Porpitce, which are more exclusively restricted 

 to warmer seas. With these was a great abundance of a small species of 

 Firoloid (Firolo'idea hyalina, D. Chiaje ?), about 0*4 inch in length, the 

 extreme transparence of which enabled every part of its organization to be 

 readily studied microscopically, its Nervous System being specially distin- 

 guishable. Of this very interesting Heteropod, a full description will be 

 hereafter published by Dr. Carpenter. 



47- The result obtained by our first Temperature-sounding in the 

 Mediterranean was fully borne out by that of the Temperature-soundings 

 taken during three subsequent days, which show an extraordinary uni- 

 formity of 6o^om-temperature at depths from 162 to 845 fathoms* : — 



* This uniformity, as we have since learned, had heen previously ohserved by Capt. 

 Spratt, in his Soundings in the Eastern Basin of the Mediterranean ; but owing (it 

 seems probable) to the want of " protection " in his Thermometers, he had set the 

 uniform temperature too high, namely 59°. (See his ' Travels and Researches in 

 Crete,' vol. ii. Appendix II.) 



74-5 

 69-3 

 65-0 

 63-0 

 617 

 597 

 55-1 

 55-0 



diff. 5-2 

 diff. 4-3 

 diff. 2-0 

 diff. 1-3 

 diff. 2-0 

 diff. 4-6 

 diff. 0-1 



