98 

is not far above that point. And it seems impossible to 
account for the latter of these facts in any other mode, than 
by assuming that Polar water is continually finding its 
way from the depths of the Polar basins along the fioor of 
the great oceanic areas, so as to reach or even to cress 
the Equator. And as no such deep efflux could continue 
to take place without a corresponding in-draught to replace 
it, a general circulation must be assumed to take place 
between the Polar and Equatorial areas, as was long since 
predicated by Pouillet. 
Such a vertical circulation, it was affirmed by Prof. 
Buff, would be necessarily caused by the opposition of 
temperature between the Equatorial and the Polar seas ; 
and this view was adopted by Dr. Carpenter, in his 
Porcupine Report of 1869, as harmonising with the tem- 
perature-phenomena which had been determined in the 
expedition of that year. It has been since contested, 
however, not only by Mr. Croll and Dr. Petermann, but 
also by Dr. Carpenter's colleague, Prof. Wyville Thomson, 
all of whom agree in regarding the amelioration of the 
temperature of the Arctic Sea as entirely due to an ex- 
tension of the Gulf Stream, the underflow of Polar water 
being merely its complement. And the authority of Sir 
John Herschel was invoked against the idea that any 
general oceanic circulation could be maintained by 
difference of temperature alone; though his statements, 
when carefully examined, only go to prove that no such 
difference could produce sevszble currents. 
Such was the state of the question when the Porcupine 
Expedition of last year concluded its work; and the 
results obtained, whilst confirmatory of previous ob- 
servations, suggested to Dr. Carpenter a definite Physical 
Theory, which now comes before us with the express ap- 
proval of the great philosopher who had been said to be 
opposed to it. 
Having ascertained, as our readers have learned from 
his report, the existence of an outward under-current in 
the Strait of Gibraltar, which carries back into the Atlantic 
the water of the Mediterranean that has undergone con- 
centration by the excess of evaporation in its basin, Dr. 
Carpenter applied himself to the consideration of the 
forces by which the superficial in-current and the deep 
out-current are sustained; and came to the conclusion 
that, as had been previously urged by Captain Maury, a 
vera causa for both is to be found in excess of evapora- 
tion, which at the same time lowers the level and increases 
the density of the Mediterranean column as compared 
with a corresponding column of Atlantic water. This 
conclusion, when scientifically worked out, was found to 
be applicable, sz¢atzs mutandis, to the converse case of 
NATURE 

the Baltic Sound ; in which, as was long ago experiment- 
ally shown (with a result that has recently been confirmed 
by Dr. Forchhammer), a deep current of salt water flows 
inwards from the North Sea, whilst a strong current of 
brackish water sets outwards from the Baltic, the amount 
of fresh water that drains into which is greatly in excess 
of the evaporation from its surface. 
Comparing, then, the Polar and Equatorial areas, it is 
shown by Dr. Carpenter that there will not only be a con- 
tinual tendency in the former to a lowering of level and | 
increase of density, which will place it in the same re- 
lation to the latter as the Mediterranean bears to the 
Atlantic ; but that the influence of Polar cold will be to 
| Fune 8, 18471 
produce a continual descent of the water within its area ; 
thus constituting the primum mobile of the General 
Oceanic Circulation, of which no adequate account had 
previously been given. This conclusion, as our readers 
will have seen, has been most explicitly accepted by 
Sir John Herschel. 
Our limits do not admit of our following Dr. Carpenter 
through his discussion of the relative shares of the Gulf 
Stream and of the General Oceanic Circulation in that 
amelioration of the temperature of the Polar area, of 
which the industry of Dr. Petermann has collected a 
vast body of indisputable evidence; and for this 
discussion we would refer such of our readers as are 
specially interested in the question to the last part 
of the “ Proceedings of the Royal Geographical Society.” 
But as Dr. Carpenter has now shown a capacity to 
deal not merely with Physiological but with Physi- 
cal questions, in a manner which has obtained the 
approval of some of the ablest physicists of our time, 
we hope that he will not again be accused (as he was by 
some of those who opposed his views on their first pro- 
mulgation) of venturing beyond his depth when he began 
to reason on these subjects, and of advancing doctrines 
which his own observations refuted. The exclusive doc- 
trine of the thermal action of the Gulf Stream advocated 
by Mr. Croll, rests, as Dr. Carpenter has shown, upon so 
insecure a basis, that a very large body of careful observa- 
tions must be collected before any reliable data can be 
obtained as to the heat it actually carries forth from the 
Gulf of Mexico. And how much of this heat is dissipated 
by evaporation, as well as by radiation, before one-half 
of the Stream reaches the banks of Newfoundland 
(the other half having turned round the Azores to re- 
enter the Equatorial current), is a question which there 
are as yet no adequate data for determining. On the 
other hand, in his conclusion that a great body of 
Ocean water slowly moving northwards, so as to carry 
with it a considerable excess of temperature even to the 
depth of 500 or 600 fathoms, must exert a much greater 
heating power than the thinned-out edge of the Gulf 
Stream, Dr. Carpenter seems to us to have both scientific 
probability and common sense on his side. 


SCIENCE IN ITALY 
Atti dell? Accademia Pontificia dé Nuovi Lincet. 
Reale Istituto Lombardo dt Scienze e Lettere. Rendi- 
conti. 
Annali di Chimica Applicata alla Medicina, Compilati 
da] Dottor Giovanni Polli. 
TALY has become a nation. It is no longer enslaved 
by the barbarous despotism, of a single city, nor 
divided into mutual throat-cutting republics, nor diplo- 
matically parcelled into heir-looms for royal families. It 
has at last become the country of its own people. The 
moral and intellectual laws of Natural Selection are now 
freely operating, and they will soon show what manner of 
people these Italians really are. 
There are many ways of gauging the civilisation of a 
community. The consumption of soap has been suggested, 
and has the advantage, being numerically definite. Thus, 
_ let s represent the quantity of soap used, # the population, | 
