Chapter LIII: Antarctic Oceanography

After the days of Sir James Ross various causes led to the development of what was almost a new science, that of Oceanography. It included not only measurement of depths, but also of the temperatures at different depths, the study of _plankton_ or surface ocean life, and of life in the depths. I remember what a revolution it caused in one’s ideas. When I went to sea we were taught that there was enormous pressure at great depths, sufficient to prevent the existence of life, for in descending the sea water got heavier and heavier under pressure. It was held that at 2000 fathoms a man would bear on his body a weight equal to 20 locomotive engines each with a goods train loaded with pig iron. The answer to this is that water is almost incompressible, so that the density of sea water at 2000 fathoms is scarcely appreciably increased. Facts send theories to the four winds.

Sir James Ross was himself much impressed with the importance of deep sea sounding with serial temperatures, and he was the first to adopt the method of sounding by time with weight and marked line, the principal conditions to ensure accuracy being rapidity of descent and regularity. The advance of the science depended on the invention of improved apparatus and instruments until they were brought to perfection.

The project of laying cables across the Atlantic gave the first impetus to these improvements. Brooke’s[198] sounding-apparatus was on the principle of disengaging weights. In 1856 the American Captain Derryman took twenty-four deep sea soundings with Brooke’s apparatus on a great circle from St John’s to Valentia. In July, 1857, Lieutenant Dayman on board H.M.S. _Cyclops_ was ordered to carry a line of soundings from Valentia to Trinity Bay, using an apparatus which was a modification of that invented by Brooke. Thirty-four soundings were taken. They were singularly uniform, 1700 to 2400 fathoms, and showed a light brown muddy sediment, and minute hard particles, animal organisms (_Foraminifera_) with skeletons composed of carbonate of lime. In the autumn of 1858 Lieutenant Dayman, in H.M.S. _Gorgon_, took another line of soundings from the S.E. angle of Newfoundland to Fayal, and from Fayal to the Channel. In the following year, in H.M.S. _Firebrand_, he took another series across the Bay of Biscay and along the coast of Portugal to Malta. Later, Captain Shortland, in H.M.S. _Hydra_, took deep sea soundings from Malta to Bombay.

Great energy continued to be shown, and in 1860 the _Bulldog_ was commissioned by Sir Leopold M’Clintock, to take a line of soundings from the Faroes by Greenland to Labrador. The sounding machine was an adaptation of Ross’s deep-sea clam with Brooke’s principle of disengaging weights. The _Bulldog_ brought up specimens from 600 to 2000 fathoms.

Hitherto oceanographic operations had been chiefly directed to the practical purpose of preparing for the laying of cables on the bed of the ocean, but the obtaining of specimens at great depths caused science to step in. Dr Carpenter and Dr Wyville Thomson were anxious to go into the whole question of the physical and biological conditions of the sea bottom, and in the autumn of 1868 the Admiralty lent the _Lightning_ gunboat, in which the two savants worked for two stormy months between Scotland and the Faroes. They found that there was abundance of animal life at the bottom of the sea, and that the fauna was in many respects peculiar. The results were considered so interesting that the Admiralty placed the _Porcupine_ gunboat at the disposal of Dr Carpenter, Dr Wyville Thomson, and Mr Gwyn Jeffreys for two successive seasons. They then succeeded in dredging to a depth of 2435 fathoms and found that even at that depth the invertebrates were fairly represented. An invention to protect the thermometer bulbs from being irregularly compressed under great pressure made the deep sea temperature determinations fairly trustworthy. Dr Wyville Thomson found that “public interest was now fairly aroused in the new field of research.”

A circumnavigating expedition was then suggested to traverse the great ocean basins, and prepare sections showing their physical and biological conditions. Mr Lowe, who was then Chancellor of the Exchequer, approved the plan, and the _Challenger_, a corvette of 2306 tons and 1234 h.-p., was selected for the service. All but two of her guns were taken out and she was fitted out entirely for deep sea sounding and dredging operations. The _Challenger_ sailed in January, 1873, under the command of Captain Nares, with Dr Wyville Thomson as head of the scientific staff. There were four Lieutenants, Maclear, Aldrich, Bromley, and Bethell, and five scientific assistants to Dr Wyville Thomson, Buchanan (Physicist) Moseley, John Murray, Willemoes-Sühn, and Wild. The ship was fitted with all the latest inventions that twenty years of study and experience had produced.

After having thrown much light on the depths and the fauna of tropical oceans, the _Challenger_ approached the Antarctic regions early in 1873. She met with dense fogs in 65° 42′ S. on February 19th, but Captain Nares continued a southward course and the vessel crossed the Antarctic Circle in 78° 22′ E. She then followed the edge of the pack for 150 miles eastward to within 15 miles of Wilkes’s supposed Termination Land. The soundings gave depths of from 1250 to 1975 fathoms. Westward of 80° E. very few icebergs were met with, but eastward of 92° E. they were very numerous. It was thought that there was no land for a considerable distance between 70° and 80° E. The depths showed that the continental shelf had not been reached on those meridians. This particular region to the east of Kempe Land has not since been visited and it offers a very interesting, and possibly a successful route for future explorers.

The science of oceanography has progressed considerably since the days of the _Challenger_; great improvements have been made in the varied apparatus connected with it, and the work has become at once more easy and more accurate. Steam power is indispensable, rendering reliable deep sea soundings possible and ice navigation much easier.

Some years after the return of the _Challenger_, the Germans despatched the _Valdivia_ on a deep sea sounding expedition. She left the Cape in November, 1898, and reached the drift ice in 56° 45′ S. Further progress was stopped in 64° 15′ S. and 54° 20′ E. A depth of 3000 fathoms was obtained, and specimens of gneiss, granite, and schist, as well as a mass of red sandstone, were brought up, probably dropped by icebergs. The ocean floor between Kerguelen Island and Enderby Land was strongly folded, a depth of 1300 fathoms alternating with great abysses of 2000 and 3000 fathoms. Many lines of soundings are still needed from the known areas near the southern extremities of America, Africa, Australia, and New Zealand to the southern continental shelves, as well as along the edges of the shelves themselves. Great progress, however, has been made in this respect within the last fifteen years, large collections have been obtained, and the Antarctic ocean depths have been sounded in several directions with important physical and biological results.