1870.] 



Deep-sea Researches. 



169 



coincident *. The specimen of bottom-water brought up by our bottle 

 was found to have a Specific Gravity of 1-0292, whilst that of the surface- 

 water was r0270. The volumetric determination of the Chlorine gave 

 21*419 per 1000 for the bottom-water, as against 20-290 per 1000 for the 

 surface-water. A decided excess of salt is thus indicated in the bottom- 

 water, as compared on the one hand with the surface-water of the same 

 spot, and on the other with the bottom-water of the Atlantic, which had 

 been generally found to show a rather smaller proportion of Chlorine than 

 the surface-water, But this excess is extremely small in comparison with 

 that indicated by Dr. Wollaston's analysis. For, assuming his factor of 

 •134 as representing, when multiplied by the excess of Specific Gravity 

 above that of distilled water, the total percentage of Salt, that percentage 

 is only 3*91, instead of 17*3 as stated by Dr. Wollaston. 



44. This result accorded so closely with that obtained by Dr. Wollaston 

 himself from the analysis of two other samples of bottom-water taken up 

 by Admiral Smyth, the one in Long. 1° 0' E. from a depth of 400 fathoms, 

 and the other in Long. 4° 30' E. from a depth of 450 fathoms, — as well as 

 with our own determinations of the Specific Gravities and Chlorine per- 

 centages of a great number of samples taken in different parts of the 

 "Western basin of the Mediterranean, — that we cannot hesitate in regarding 

 it as representing the ordinary condition of the bottom-water at this spot. 

 And it seems to us far more probable that the sample furnished by Admiral 

 Smyth to Dr. Wollaston had been concentrated by evaporation in a badly 

 stopped bottle, in the three years during which it had remained in Admiral 

 Smyth's possession, than that any extraordinary discharge of salt from a 

 brine-spring at the bottom (a sort of Deus ex machind invoked by Admiral 

 Smyth to account for the .occurrence) should have given rise, in the spot 

 at which his Sounding was taken, to an exceptional condition of which no 

 indication whatever was presented in our own. 



45. The Temperature-phenomena presented at this Station proved of 

 singular interest. The s^r/ace-temperature, 74°- 5, was higher than any 

 that had been encountered on the Atlantic side of the Straits, even in a 

 latitude half a degree further south ; and the observations, which had been 

 regularly taken every two hours, showed that it had increased nearly ten 

 degrees as we proceeded eastwards from Station 39, between 10 a.m. and 

 2 p.m. A part of this increase was doubtless due to the heating effect of 

 the mid-day sun ; but as the temperature of the air had not increased quite 

 six degrees during the same time, and as it will be shown hereafter (§ 86), 



* Thus Admiral Smyth states (Mediterranean, p. 159) the depth in mid-channel 

 between Gibraltar and Ceuta to be 950 fathoms ; whereas it is now known to be but 

 little more than 500 fathoms. " A little further to the eastward," he says, " there is no 

 bottom with 1000 fathoms of line up-and-down (upwards of 1300 payed out) ;" whereas 

 the greatest depth as far east as Malaga Bay is now known not to exceed 750 fathoms. 

 These errors are noticed in no invidious spirit, but merely to prevent their perpetua- 

 tion. Admiral Smyth doubtless made the very best use of the means at his disposal ; 

 but a far more satisfactory method has now entirely superseded that formerly adopted. 



