224 
108 pages, with numerous maps and diagrams, by the 
new Oceanographical Institute in Berlin and the 
Geographical Institute of the University of Berlin, under 
the direction of the head of both institutions, Baron F. 
von Richthofen.!. The work, though mainly of value in 
the instruction it afforded the workers, still constitutes a 
contribution to our knowledge of the Atlantic, and pro- 
mises well for the scientific harvest which we hope the 
Gauss has by this time begun to reap in less known 
waters. 
The memoir consists of four parts—a general report of 
the expedition by the leader, Prof. E. von Drygalski, 
seven reports on the scientific work by the various 
specialists on board, technical reports by the chief 
engineer and the captain of the ship, and finally a special 
report on the establishment of the auxiliary station at 
Kerguelen. 
As the investigators on the Déscovery brought them- 
selves into working order by monographing the island of 
South Trinidad, those on the Gauss set about the general 
description of St. Vincent in the Cape Verde group as 
their first exercise. Dr. Emil Werth describes the 
topography and types of vegetation of the island, and 
Dr. Philippi gives a brief account of the geology. The 
island is described as an ancient volcano, the central 
plain corresponding to the crater, the rim of which 
survives in parts as a peripheral mountain-chain. 
The more systematic work of the expedition commences 
with Prof. von Drygalski’s report on the oceanographical 
observations which were his special care. As far as the 
equator these were confined to the surface, but from the 
equator southwards deep-sea observations were added at 
regular intervals, along the course which lay alternately 
a little to the west and a little to the east of the meridian 
of 20° E. The superficial conditions are very ingeniously 
shown by means of curves drawn on the map of the 
route, the abscisse being the projection of the track on 
the meridian and the ordinates the values of temperature, 
salinity and density 77 sz¢u. The surface temperature, 
closely following that of the air, rose steadily from 17° C. 
at the mouth of the English Channel to an average of 27° 
in the Doldrums (16° N. to 5° N.), then fell to 24° at the 
equator and remained steady to 15° S., after which it fell 
steadily, reaching 18° C. in 30° S. The salinity curve 
showed maxima in the tropics both north and south, 
separated by a minimum in the belt of calms at 7° N. 
The density of surface-water 77 sz¢z remained constant 
between the temperate zone and the tropics in both 
hemispheres, but fell to a single minimum in the equa- 
torial belt of calms, where the maximum temperature 
met the minimum salinity. Samples for the determina- 
tion of density and chlorine were collected every four 
hours and a number of different methods were employed 
for making the determinations. Titrations of chlorine 
were controlled by Knudsen’s standard samples of sea- 
water, which were supplied to the expedition for the 
purpose. In addition to two patterns of direct-reading 
hydrometers, a set of Nansen’s total-immersion hydro- 
meters by the use of which the troublesome factor of 
surface-tension is eliminated were utilised, and a 
refractometer was also employed for the optical determina- 
tion of the density of the sea-water. The value of the 
salinity deduced by Knudsen’s tables from the chlorine 
determinations was always found a little lower than when 
deduced from hydrometer or refractometer observations ; 
the mean error of the determinations was found to be 
least for titration of chlorine and greatest for the refracto- 
meter. The chief difficulty with regard to that instrument 
was found to be the temperature correction ; but Prof. v. 
Drygalski points out the very decided advantage of the 
immersion refractometer with which the Gauss is pro- 
vided over the differential refractometer formerly used. 
_1 Bericht iiber die wissenschaftlichen Arbeiten auf der Fabrt von Kiel bis 
Kapstadt und die Errichtung der Kerguelen Station. 
NO. 1705, VOL. 66] 
NATURE 
[JuLY 3, 1902 
The colour of the sea-water was systematically ob- 
served, but the range of Forel’s xanthometer being 
found insufficient, the more extensive scale of colours 
used by Luksch on the Pola expedition was adopted 
instead, 
Deep-sea soundings were made with a modified 
Sigsbee machine. Using a detaching weight of 35 
kilogrammes as a sinker, soundings were completed in 
5000 metres (2770 fathoms) in seventy minutes in calm 
weather. Prof. v. Drygalski found the Negretti and 
Zambra reversing thermometer unsatisfactory for deep 
soundings, on account of the shaking of mercury out of 
the inverted bulb in hauling up through the hot tropical 
surface-water. The Miller-Casella thermometers, on the 
other hand, acted admirably, and he regretted not having 
taken a larger supply. We think, however, that in the 
very different conditions of the polar seas this opinion of 
the relative utility of the two types of instrument will 
very likely be reversed. 
On the voyage between 37° N. and 34° S. no fewer 
than thirty successful deep-sea soundings were taken, of 
which nine gave depths exceeding 5000 metres (2770 
fathoms), and the deepest as much as 7230 metres (3950 
fathoms). The positions of the soundings were chosen 
so as to throw light on special problems of suboceanic 
configuration. 
Opportunity was taken to test the Pettersson-Nansen 
insulating water-bottle in these depths, and the result 
was to show that the great contrast of temperature 
between the bottom and surface in the tropical seas was 
too much for the power of insulation, and that the inner 
cylinder of water altered its temperature somewhat before 
a reading could be made. This difficulty will, of course, 
not be experienced in the more uniform temperatures of 
polar seas. 
An interesting fact brought out by the determination 
of salinity as well as temperature at each point of obser- 
vation was that about the depth of 800 metres, where the 
sudden change in the temperature curve occurs between 
the warm upper and the cold lower waters, there occurs 
an actual inversion of the salinity curve, showing that a 
stratum of minimum salinity is interposed between the 
two salter layers. 
The study of oceanic deposits brought out some new 
facts, and suggests problems not very easy of solution. 
By using sounding tubes of 2 or 3 centimetres 
diameter.and 200 centimetres long some very long cores 
were obtained. One of these, from the depth of 7230 
metres (3950 fathoms), in o° 11’ S., 18° 15’ W., showed 
distinct stratification. The core was 46 centimetres long ; 
the uppermost 13 centimetres consisted of red clay con- 
taining numerous fragments of volcanic rock, then 
followed in order four bands of different colour, passing 
from brownish-grey to dark and then light grey. The 
dark grey layer distinctly resembled a terrigenous deposit, 
and the light grey jayer, the lowest of all, was the only 
one containing a perceptible proportion of calcium car- 
bonate. The bearing of this observation on past changes 
in the configuration of the ocean and the distribution of 
land is pointed out. A still more curious specimen was 
a core 69 centimetres (say 2 feet) long, obtained in 
35° 52’ S., 13° 8’ E., from a depth of 4957 metres (2750 
fathoms). The uppermost 11 centimetres consisted of a 
brown. clayey quartz sand with very little volcanic or 
calcareous material, while the next 12 centimetres were 
almost pure globigerina ooze with fragments of the upper 
layer, and the greater mass of the section consisted of 
material similar to the upper layer, but with the clayey 
material predominating over the sand. Dr. Philippi 
could not account for this appearance of sand in a 
pelagic deposit by considerations of the prevailing wind 
(which blows towards, not from, the South African 
deserts), or by currents, so he is driven to suggest that 
the material is ice-borne, though he acknowledges the 
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