’'* 
Fan. 9, 1873] 
‘THE SCIENTIFIC ORDERS OF THE 
“ CHALLENGER” 
ie 
WE have received from the Admiralty permission to 
publish the following Report of the Circumnaviga- 
tion Committee of the Royal Society, on the work which 
lies before the Challenger Expedition. We are sure its 
perusal will gratify all our readers. 
The principal object of the proposed expedition is understood 
to be to investigate the physical and biological conditions of the 
great ocean-basins ; and it is recommended for that purpose to 
pass down the coast of Portugal and Spain, to cross the Atlantic 
from Madeira to the West Indian Islands, to go to Bermuda, 
thence to the Azores, the Cape de Verde Islands, the coast of 
South America, and across the South Atlantic to the Cape of 
Good Hope. Thence by the Marion Islands, the Crozets, and 
Kerguelen Land, to Australia and New Zealand, going south- 
wards ev route, opposite the centre of the Indian Ocean, as near 
as may be with convenience and safety to the southern ice- 
barrier. From New Zealand through the Coral Sea and Torres 
Straits, westward between Lombok and Bali, and thence through 
the Celebes and Sulu Seas to Manilla, then eastward into the 
Pacific, visiting New Guinea, New Britain, the Solomon Islands ; 
and afterwards to Japan, where some considerable time might be 
profitably spent. From Japan the course should be directed 
across the Pacific to Vancouver Island, then southerly through 
the eastern trough of the Pacific, and homewards round Cape 
Horn. This route will give an opportunity of examining many 
of the principal ocean phenomena, including the Gulf-stream and 
equatorial currents ; some of the biological conditions of the sea 
of the Antilles; the fauna of the deep water of the South At- 
lantic, which is as yet unknown, and the specially interesting 
fauna of the borders of the Antarctic Sea. Special attention 
should be paid to the botany and zoology of the Marion Islands, 
the Crozets, Kerguelen Land, and any new groups of islands 
which may possibly be met with in the region to the south-east 
of the Cape of Good Hope. Probably investigations in these 
latitudes may be difficult ; it must be remembered, however, that 
the marine fauna of these regions is nearly unknown, that it must 
bear a most interesting relation to the fauna of high northern 
latitudes, that the region is inaccessible except under such cir- 
cumstances as the present, and that every addition to our know- 
ledge of it will be of value. or the same reasons the expedition 
should, if possible, touch at the Auckland, Campbell, and 
especially the Macquarie Islands. Particular attention should 
be paid to the zoology of the sea between New Zealand, Syd- 
ney, New Caledonia, and the Fiji and Friendly Islands, as it is 
_ probable that the Antarctic fauna may be found there at acces- 
sible depths. New Britain and New Ireland are almost un- 
known, and from their geographical position a special interest 
attaches to their zoology, botany, and ethnology. The route 
through this part of the Pacific will give an opportunity of check- 
ing and repeating previous observations on the structure of coral 
reefs and the growth of coral, and of collecting series of volcanic 
_ rocks. The Japan current will also be studied, and the current 
along the coast of California. The course from Japan to Van- 
couver Island and thence to Valparaiso will afford an opportunity 
of determining the physical geography and the distribution of 
life in these regions, of which at present nothing is known. 
1.—Physical Observations 
In crossing the great ocean basins observations should be 
made at stations the positions of which are carefully determined, 
chosen so far as possible at equal distances, the length of the 
intervals being of course dependent on circumstances. At each 
station should be noted the time of the different observations, 
the state of the weather, the temperature of the surface of the 
sea, the depth, the bottom temperature determined by the mean 
of two Miller-Casella thermometers, the specific gravity of the 
surface- and bottom-waters. The nature of the bottom should 
be determined by the use of a sounding-instrument constructed 
to bring up samples of the bottom, and also, if possible, by a 
haul of the dredge. When practicable, the amount and nature 
of the gases contained in the water, and the amount and nature 
of the salts and organic matter should be ascertained. As fre- 
quently as possible, especially in the path of currents, serial tem- 
perature-soundings ought to be taken cither with the instrument 
NATURE 
19! 
of Mr. Siemens, or with the Miller-Casella thermometer, and in 
the latter case at intervals of 10, 50, or 100 fathoms, to deter- 
mine the depth and volume of masses of moving water derived 
from different sources. 
The simple determination of the depth of the ocean at tole- 
rably regular distances throughout the entire voyage is an object 
of such primary importance that it should be carried out when- 
ever possible, even when circumstances may not admit of dredg- 
ing, or of anything beyond sounding. The investigation of 
various problems relating to the past history of the globe, its 
geography at different geological epochs, and the existing dis'ri- 
bution of animals and plants, as well as the nature and causes of 
oceanic circulation, will be greatly aided by a more accurate 
knowledge of the contour of the ocean-bed. 
Surface- Temperature.—The surface-temperature of the sea, as 
also the temperature of the air as determined by the dry- and 
wet-bulb thermometers, should be regularly recorded every two 
hours during the day and night throughout the voyage. 
These records should be reduced to curves for the purpose of 
ready comparison ; and the following points should be carefully 
attended to :— 
1. In case of a general correspondence between the tempera- 
ture of the sea and that of the air, it should be noted whether in 
the diurnal variation of both, the sea appears to /o//ow the air, 
or the air the sea. 
2. In case of a marked discordance, the condition or con- 
ditions of that discordance should be sought in (a) the direction 
and force of the wind, (2) the direction and rate of movement of 
the ocean surface-water, (c) the hygrometric state of the atmo- 
sphere. When the air is very dry, there is reason to believe 
that the temperature of the surface of the sea is reduced by 
excessive evaporation, and that it may be below that of the sub- 
surface stratum a few fathoms deep. It will be desirable, there- 
fore, that every opportunity should be taken of comparing the 
temperature at the surface with the temperature of the subsurface 
stratum—say at every 5 fathoms down to 20 fathoms. 
Temperature-Soundings.—The determination of the tempera- 
ture, not merely of the bottom of the ocean over a wide geogra- 
phical range, but of its various intermediate strata, is one of the 
most important objects of the expedition ; and should, therefore, 
be systematically prosecuted on a method which should secure 
comparable results. The following suggestions, based on the 
experience already obtained in the North Atlantic, are made for 
the sake of indicating the manner in which time and labour may 
be economised in making serial soundings, in case of the employ- 
ment of the Miller-Casella thermometer. They will be specially 
applicable to the area in which the work of the expedition will 
commence; but the thermal conditions of other areas may 
prove so different, that the method may need considerable modi- 
fication. 
The following strata appear to be definitely distinguishable in 
the North Atlantic :—(a), a “superficial stratum,” of which the 
temperature varies with- that of the atmosphere, and with the 
amount of Insolation it receives. The thickness of this stratum 
does not seem to be generally much above 100 fathoms, and the 
greatest amount of heating shows itself in the uppermost5o0 fathoms, 
(4) Beneath this is an “ upper stratum,” the temperature of which 
slowly diminishes as the depth increases down to several hundred 
fathoms ; the temperature of this stratum, in high latitudes, is 
considerably adéove the normal of the latitude ; but in the inter- 
tropical region it seems to be considerably de/ow the normal. 
(c) Below this is a stratum in which the rate of diminution of 
temperature with increasing depth is rapid, often amounting to 
10° or more in 200 fathoms. (@) The whole of the deeper part 
of the North Atlantic, below 1,000 fathoms, is believed to be 
occupied by water not many degrees above 32°. With regard to 
this ‘glacial stratum,” it is exceedingly important that its depth 
and temperature should be carefully determined. 
It will probably be found sufficient in the first instance to take, 
with each deep Joffom sounding, seria’ soundings at every 250 
fathoms, down to 1,250 fathoms ; and then to fill up the inter- 
vals in as much detail as may seem desirable. Thus where the 
fall is very small between one 250 and the next, or between any 
one and the bottom, no intermediate observation will be needed ; 
but where an abrupt difference of several degrees shows itself, it 
should be ascertained by intermediate observations whether this 
difference is sudden or gradual. 
The instrument devised by Mr. Siemens for the determination 
of submarine temperatures is peculiarly adapted for serial 
measurements, as it does not require to be hauled up for each 
