333 

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 1°0270. The volumetric determination of the 
chlorine gave 21°419 per I,000 for the buttom-water, as against 
20°290 per I,000 for the surface-water. A decided excess of salt 
is thus indicated in the bottom-water, as compared on the one 
hind with the surface-water of the same spot, and onthe 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 per-centage 
of salt, that per-centage is only 3°91, instead of being 17°3, as 
stated by Dr. Wollaston. 
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° 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 determina- 
tions 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 
Tepresenting the ordizary 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 con- 
centrated by evaporation in a badly-stopped bottle in the three 
years during which it had remained in Admiral Smyth’s pos- 
session, 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 pre- 
sented in our own. 
The temperature-phenomena presented at this Station proved 
of singular interest. The szfuce-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 farther south; and the 
observations which had been regularly taken every two hours 
showed that it had increased nearly tex degrees as we proceeded 
eastwards from Station 39, between Io 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 séx degrees during the same time, and as it will be shown 
hereafter by a comparison of the diurnal averages of the 
surface temperature of the Mediterranean with those of the At- 
lantic, 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 Jéoffom-temperature was found 
to be here 55°; and this corresponded closely with that which we 
had met with in the Strait, 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 
seria/ soundings at intervals of 10 fathcms down to 50, and then 
at 100 fathoms ; with the following remarkable result :— 

” 
586 ” 
Thus there was a fall of 9°°5 in the first 20 fathoms ; of 5°°3 in 
the next 30 fathoms ; of 4°°6 in the next 50 fathoms ; whilst from 
100 fathoms to the bottom at 586 fathoms there was no further 
descent. 
Whilst we were prosecuting these inquiries, we found ourselves 
surrounded— the surface of the sea being extremely calm—by 
great numbers of the beautiful floating Ve/e//e, which are occa- 
sional yisitors to our own coast, accompanied by the Porfite, 
which are more exclusively restricted to warmer seas. With 
these was a great abundance of a small species of ivo/a, about 
04 inch in length, the extreme transparence of which enabled 
every part of its organisation to be readily studied microscopi- 
cally, its nervous system being specially distinguishable. Of this 
(bottom) ... 
NATURE 


[Feb. 23, 1871 

very interesting Heterofod, a full description will be hereafier 
published by Dr. Carpenter. 
The result obtained by our first temperature-sounding in the 
Mediterranean, was fully borne out by that of the tempe- 
rature-soundings taken during three subsequent days ; which 
show an extraordinary uniformity of 4o¢/om-temperature at depths 
from 162 to 845 fathoms * :— 
7 Depth, Surface- Bottom- 
Station. in faths, temp. temp. 
No. 2 4 
4 74°5 55'0 
42 7470 5470 
43 74°7 55°0 
44 70°0 55°0 
45 72°77 54°7 
46 FS 55°5 
47 69°5 54°7 

It will be observed that the surface temperature varied between 
69°'5 and 74°°5; and that whilst the highest temperatures were 
shown at Stations near the African coast, the lowest presented 
itself between Cape de Gat and Cartagena. Now the Gibraltar 
inflow is very sensibly felt at Cape de Gat, where the current 
usually runs at the rate of amile an hour; and of the strength 
of this current we had unpleasant experience. For on the 19th 
of August, as we were crossing from Station 46 towards tho 
Spanish coast, we encountered a strong N.E. breeze, which, 
mecting the current, worked upa considerable swell ; this pre- 
vented us from taking even a temperature-sounding on that day, 
and gave our ship a peculiar twisting or screwing movement, 
from which we were glad to escape by the subsidence of the 
breeze during the following night. During this day the surface- 
temperature of the sea came down from the average of 72°*2 which 
it had maintained on the 18th, to66°°9. Had the weather been calm, 
we might have attributed this reduction to the colder Gibraltar in 
current ; but as the average temperature of the air also fell from 
73°'8 to 69°°8, and as the strong N.E. breeze must have had a 
cooling effect upon the surface of the sea, we should have deemed 
it probable that the reduction of surface-temperature was due at 
least as much to the latter as to the former of these causes, had it 
not been that a set of serial soundings which we took at Station 
47 showed that the reduction extended very far down, as will be 
apparent on comparing the following results with those previously 
given :— 



Surface 
10 fathoms... 
20 ” 
: ce ae 
49:5 3 
50 ” 
TOO: ‘35 A 
845 ss “ 
It will be seen hereafter that the observations made on our 
return voyage gave more distinct evidence of the cooling influence 
of the Gibraltar in-current. 
At most of these stations we explored the bottom by means of 
the dredge, with results much less profitable than we had antici- 
pated. Except near the coast, on either side, where the ground 
was rocky and unequal, the bottom was found everywhere to 
consist of a tenacious mud, composed ofa very fine yellowish 
sand mixed with a bluish clay—the former predominating in 
some spots, the latter in others. Large quantities of this mud 
were laboriously sifted, often without yielding anything save a 
few fragments of shells, or a small number of Foraminifera ; and 
in no instance was it found to contain any considerable number of 
living animals of any description. Our disappointment at this 
unexpected paucity of life was not small; and it was destined, 
as will hereafter appear, to continue through the whole of our 
dredging exploration of the deeper portions of the Mediter- 
ranean basin. The operation of dredging in the shallower por- 
tions nearer shore was rendered difficult by the rocky nature of 
the bottom, on which the dredge continually ‘‘ fouled ;” and after 
the loss of two more dredges anda considerable quantity of rope, 
Capt. Calver came to the conclusion that the ‘‘ tangles” only 
should be used where the inequality of the soundings indicated 
danger to the dredge. Now the “tangles,” whilst gathering 
* This uniformity, as we have sii ce learned, had been previously observed 
by Captain Spratt, in his Soundings in the Eastern Basin of the Mediter- 
ranean ; but owing it seems probable to the want of “protection” in his 
thermometers, he had set the uniform temperature too igh, namely 59. 
(See his “Travels and Researches in Crete,” vol ii. Appendix IL) : 
