580 



Dr. W. B. Carpenter on the 



[June 13, 



nearly the whole of this excess it retains to the bottom at 1650 fathoms. 

 The rate of reduction in No. II. differs from the preceding in being much 

 more rapid between 10 and 20 fathoms; the reduction in that stratum 

 being 9°'5, as against 4°*3 in No. I., and 3°'6 in No. III. And this de- 

 pression extends to the subjacent strata ; the temperature falling almost to 

 its minimum at 50 fathoms. On the other hand in No. IV. the tempera- 

 ture of the upper stratum shows a much less rapid reduction than in either 

 No. I., II., or III. ; the high surface-temperature being carried down to 

 30 fathoms with a loss of only 3^°. Between 30 and 40 fathoms, however, 

 the reduction is more considerable, amounting to 6|-° ; but from this depth 

 to 60 fathoms, the temperature is still about six degrees higher than at the 

 like depth in No. III. ; and whilst at 60 fathoms the temperature in No. 



III. is only 3°'7 above that of the bottom, it is 8°'8 above that of the 

 bottom in No. IV. Whilst in No. III., however, the further reduction 

 takes place very slowly, so that the temperature only falls 1°*2 between 

 60 and 100 fathoms, there is a fall of 6° in this stratum of No. IV., which 

 brings down the temperature at 100 fathoms to within one degree of the 

 temperature at the same depth in No. III. A slight excess appears to be 

 maintained at yet greater depths ; the temperature at 200 fathoms being 

 2° higher in No. IV. than in No. III., and being still 1°"8 higher in No. 



IV. than the temperature of the bottom, whilst in No. III. it is at that 

 depth only o, 5 higher; and the bottom-temperature of No. IV., even at 

 a depth of 1970 fathoms, was 0*7 in excess of the bottom-temperature of 

 No. III. at 1650 fathoms. 



69. It would thus appear : — (1) that the high surface-temperature which 

 we met with during the early part of October, in proceeding from Malta to 

 Alexandria, extended to a much greater depth in Long. 26° 44' E. than it 

 did in Long. 16° 23' E. ; (2) that the stratum of which the temperature is 

 considerably raised by insolation was much thicker at the former than at 

 the latter station ; and (3) that the temperature of the stratum between 

 100 and 200 fathoms still exhibits in the Eastern basin some evidence of 

 being influenced by direct insolation, the bottom-temperature which is met 

 with in the Western basin at all depths below 100 fathoms being here not 

 encountered until 200 fathoms have been passed. 



70. How far these differences are due to the different conditions of the 

 Eastern and Western basins, or are attributable to the remarkable prolon- 

 gation of a high Summer temperature in the season of 1871, is a point 

 which can only be determined by a much more extended series of observa- 

 tions. There are, however, some considerations which may help us to a 

 probable conclusion. — In the first place, it appears certain that a higher 

 surf etc e-tem-per&ture prevails over the Eastern basin generally than over the 

 Western. This is doubtless partly due to its lower Latitude ; for whilst the 

 axis of the Western basin may be considered to correspond with the parallel 

 of 38°, that of the Eastern corresponds with the parallel of 34°. But what 

 has probably a yet greater effect, is the absence along the Eastern portion 



