Notices of Books . 
124 
[January, 
the southern hemisphere, from which a coicl under-current is 
steadily flowing northwards. This arrangement depends on the 
circumstance that the rainfall in the Southern sea is in excess of 
evaporation, whilst in the North Atlantic and Pacific the reverse 
rule holds good. The temperature of the Atlantic does not 
ippear sensibly affected by any influx of cold water from the 
ArcStic Sea. The greatest depth found in the Atlantic — 3875 fa- 
thoms, an abyss in which Chimborazo would be “ taken over- 
head ” — was observed a little to the north of the Virgin Islands. 
At all depths between 400 and 2000 fathoms the bottom of the 
Atlantic — save where the debris brought down by rivers or due 
to the disintegration of rocks interferes — is covered with 
“ Globigerina-ooze,” a calcareous deposit mainly produced by 
the shells of Foraminifera, but mixed with fragments of pumice, 
felspar, sanidine, angite, hornblende, quartz, leucite, and mag- 
netite, generally in very small particles. As the globigerina-ooze 
is decomposed, it gradually passes into so-called “ red clay,” 
more or less homogeneous, which covers the floor of the deep 
depressions below the 2000-fathom level. In this substance 
recognisable mineral fragments were found in greater abundance. 
The pieces of pumice were most numerous in the neighbourhood 
of well-known volcanic centres, such as the Acores and Philip- 
pines, and they are supposed to be all due to sub-aerial volcanic 
action. It does not appear easy to identify any of the beds now 
in course of formation at the bottom of the ocean with the rocks 
belonging to any of the past geological periods. The rocks of 
the Mesozoic and Kainozoic series seem to have been formed in 
shallow water. The author believes, however, that the globi- 
gerina-ooze, if elevated and slightly metamorphosed, would 
yield a limestone very closely resembling a bed of grey chalk, 
whilst the “ red clay,” under similar circumstances, might ap- 
proximate closely to one of the palaeozoic schists. He does not 
wish, however, to offer a definite opinion until the comparative 
chemical and microscopic examination of the specimens dredged 
up is completed. 
The volumes before us must produce a favourable impression 
upon every candid reader. Though necessarily “ dry ” in parts, 
they are perfectly free from any gratuitous parade of technical- 
ities, as well as from “ fine writing,” and, above all, from any 
obtrusion of the author’s personality. Sir Wyville Thomson 
sees, and tells us what he sees, without “ posing ” for our ad- 
miration. The work is also not like too many records of voyage 
and travel, ballasted with irrelevancies. If we further bear in 
mind that we have here merely an instalment, and that probably 
the less interesting part of the work done by the “ Challenger,” we 
must pronounce the results of the highest service to Science, 
and creditable to the Government which sent out the Expedition, 
to the illustrious Society by which it was planned, and to the 
eminent men by whom so arduous a task was successfully 
executed. 
