2€0 
OCEANOGRAPHICAL INVESTIGATIONS IN 
SOUTH AFRICAN WATERS. 
‘THE observations published in the pamphlet of which the 
title is given below are the first of a series undertaken in 
connection with the fishery investigations recently inaugurated 
at the Cape. They include observations made in March and 
April, 1900, by the Government steamer eter Faure, con- 
sisting of temperatures and analyses of water samples from 
points to the west of the Cape Peninsula; observations of | 
surface temperature made on February rr to 18 and March 3, | 
1898, at intervals of about five miles, to a distance of fifty 
miles west of Cape Town, andona voyage to St. Helena Bay ; 
daily records of air and sea temperatures taken at Robben 
Island in Table Bay, and at Roman Rock in Simon’s Bay 
during the three years 1898-1900; temperatures and analyses 
of water samples taken at intervals on passages of the Govern- 
ment trawler between Table Bay and Simon’s Bay, and of mail 
steamers between Table Bay and Cape Hangklip. An extended 
series of observations is now in progress over the whole of the 
South African coast. 
The investigation of which this forms the beginning is, with- 
out doubt, one of the most valuable and important of its kind 
ever attempted. The preliminary international work which 
has been carried on in the North Sea and the Baltic during the 
last nine years, and is now about to take definite shape as an 
organised system of research, has shown that adequate hydro- 
graphical observations are of the utmost value, not only in them- 
selves as determining the circulation of waters, but in their 
relation to climatology and to fishery work of all kinds. Similar 
research in South African waters has the additional interest of 
dealing with a region where the current system is not only un- 
usually complex, but is very strongly and clearly developed ; 
and the fact that the services of a special ship are available 
renders the opportunity of studying the relations existing 
amongst the different current elements unique. 
Unfortunately, however, the methods employed in the present 
series of observations seem to leave much to be desired. 
Nothing is said about the thermometers employed in taking tem- 
peratures, or about their corrections, and the observations at 
different depths are made with little reference to the changes of 
temperature ; many of them are unnecessary, and there are 
frequent gaps which leave the true form of the temperature 
curve undetermined. The curves and sections shown suggest that 
the boundaries between masses of water are often very sharply 
defined, and that a high degree of accuracy, in the instruments 
employed, in their working, and in the determinations of ship’s 
position, is essential. The laboratory analyses of the samples 
of water collected are still more unsatisfactory. In most cases 
the chlorines have been determined, by a method not stated, 
and the results are, for a reason left unexplained, expressed in 
grains per gallon, thereby rendering them incomparable with 
any other determinations except those of county analysts. A 
study of the chlorine values in relation to their geographical dis- 
tribution does not inspire confidence in the accuracy of the deter- 
minations, and the uncertainty increases on comparison with the 
values in columns headed ‘specific gravity” and ‘‘ 
oxide.” No account is given of the methods by which the 
specific gravity determinations have been made, nor is there 
any statement as tothe temperatures to which they are referred, 
and we find, for example, such records as the following :— 
Temp. Specific Chlorine in grains 
2193 gravity. per gallon 
63°00: oJ 1°02712 1412°0 
O3KOM ver 102696 1414°5 
63/0 1'02700 1409°5 
6370 1‘02700 1422°0 
63:0 1°02696 1402°0 
630 1°02723 1414°5 
The determinations of sulphuric oxide, which are, presumably, 
also stated in grains per gallon, give, on a series of averages 
(p. 215), values of the chlorine ratio ranging from 11°8 to 12°2, 
and on a single set (p. 213) from 10°4 to 131. Such determi- 
nations fall distinctly short of the standard required for work 
of the kind, and as there is no continuity in the variations, 
we must regard the whole of the tabular matter in the paper 
_1“Cape of Good Hope. 
tions in South Africa. 
the Sea around 
B.Sc., Ph.D. 
NO. 1706, VOL. 66] 
Department of Agriculture. Marine Investiga- 
Observations on the Temperature and Salinity of 
the Cape Peninsula.” By J. D. F. Gilchrist, M.A., 
NATURE 
sulphuric | 
[JuLY 10, 1902 
with considerable suspicion. Finally, we note that in a region 
where meteorological observations are of the greatest interest 
and value, a specially equipped scientific expedition makes its 
barometer readings ‘‘ direct from Aneroid.”” 
We direct attention to these points because the importance 
of the work imperatively requires that it should be thoroughly 
well done when there is an opportunity of doing it at all. The 
detailed reports on methods, published by participants in the 
| international work already mentioned, and the tables produced 
by Knudsen under the direction of the International Committee, 
leave no excuse for doing it otherwise. 
A NEW FORM OF SEISMOGRAPH. 
N the Bollettino della Socteta Sismologica Italiana (vol. vii. 
No. 7), Dr. G. Agamennone gives a detailed description 
of a seismograph, consisting of two horizontal pendulums each 
of which carries a mass of 14 kg. and.a vertical spring seismo- 
graph with a mass of 2kg., which write their records side by 
side on a band of smoked paper 25 cm. broad. 
oa 
A reference to the accompanying figure shows the manner in 
which these three well known pieces of apparatus, which stand on 
abed plate 55 cm. square, arearranged. The screws w alter the 
inclination of the vertical axes of the horizontal pendulums and 
hence their period. The screws U are to give horizontal ad- 
justment for the same. By shifting the position of the weights 
MM, assuming the same to coincide with centres of oscillation, 
the multiplication of the writing pointers, which are at the ex- 
tremities of arms attached at 45° to those carrying the weights, 
may be made twice that of the movement of the ground. It is 
| almost needless to remark that with so small an amplification 
the instrument is only intended to record earthquakes which 
can be felt and are severe. When such an earthquake occurs, 
the electromagnet F is brought into action to release the clock- 
work, and the smoked paper then moves beneath the writing 
pointers at a rate of 25 metres per hour—a speed sufficiently 
high to give an open diagram of vibrations with periods of 1/1oth 
second. But is it not desirable to record vibrations with a 
frequency greater than 10 per second, and in addition to obtain 
a trace of the preliminary tremors? Dr. A. Cancani, who uses 
films which move continuously at a rate of 6 metres per hour, 
obtains something to show the latter, but the rate is not suffi- 
ciently high to give open records of movements the period of 
which is very short. Then again, it must not be overlooked 
that the large movements of severe earthquakes are undulatory 
| in character, and both horizontal pendulums and vertical spring 
—] 
