173 REPORT— 1876. 



through the medium of g-raphical reuderiug on charts auil concise textual descrip- 

 tions, cannot he overrated ; still much is wanting in fulness and precision of detail, 

 especially in those distant but limited regions more receutlj^ opened out by expand- 

 ing trade. Science views, too, with increasing interest these advances in our 

 knowledge of ocean pliysics, as bearing materially on the grand economy of nature : 

 essays, brilliant and almost exhaustive on some of its subjects, have been given to 

 us by eminent men of our own day ; but here one is reminded, by the diversity in 

 the rendering of facts, how much remains to be done in their correlation, and 

 what an extensive and still expanding held is before us. 



The dawning eflbrts of science to pass beyond the immediate practical require- 

 ments of the navigator are worthy of note. "We find — from an admirable paper 

 On the "Temperatures of the Sea at different Depths,'' by Mr. Prestwich, j ust 

 published in the Philosophical Transactions — that in the middle of last century 

 the subject of deep-sea temperatures first began to attract attention, and ther- 

 mometers for the pm'pose were devised ; but it was not till the early part of the 

 present century that the curiosity of seamen appears to have been generally 

 awakened to know more of the ocean than could be gleaned on its surface. John 

 Ross, when in the Arctic seas in 1818, caught glimpses of animal life at the depth 

 of 6000 feet ; other navigators succeeded in obtaining the temperatm'e of succes- 

 .sive layers of water to depths exceeding GOOO feet ; but, so far as I can ascertain, 

 James Ross was, in 1840, the first to record beyond doubt that bottom had been 

 reached, " deeper than did ever plummet sound," at lfi,OGO feet, westward of the 

 Cape of Good Hope 



The impetus to deep-sea exploration, however, was given by the demand for 

 electrical telegraphic communication between coimtries severed by the ocean or by 

 impracticable land routes ; and the past twenty years marks its steady growth. 

 Appliances for reaching the bottom with celerity, for bringing up its water, for 

 bringing up its formation, for registering its thermal condition in situ, have 

 steadily improved ; and thus the several oceans were examined both over present 

 and prospective telegraph-routes. Science, aroused by the consideration that vast 

 fields for biological research were opening up — as proved by the returns, prolific 

 with living and dead animal matter, rendered by the comparatively puny appliances 

 originally used for bringing up the sea-bottom — invoked, as beyond the reach of 

 private enterprise, the aid of Government. Wiseh", earnestly, and munificently 

 was the appeal responded to ; and thus the ' Challenger ' expedition has become 

 the culminating effort of our own day. 



AVe have now reached, in all probability, a new" starting-point in reference to 

 many of our conceptions of the physics of the globe ; and om- own special branch may 

 not be the least affected. There is opened up to us, for example, as fair a general 

 knowledge of the depression of the bed of large oceanic areas below the sea-level, 

 as of the elevation of the lauds of adjacent continents above that universal zero-line. 

 We learn for the first time by the ' Challenger's ' results — ably supplementijd a.s 

 they have recently been by the action of the U.S. Government in the Pacific, and 

 by an admirable series of soundings made in the exploratory German ship of war 

 ' Gazelle ' — that the unbroken range of ocean in the southern hemisphere is mucli 

 shallower than the northern seas, that it has no features approaching in character 

 those grand abyssal depths of 27,OCO and 23,.500 feet found respectively in the 

 North Pacific and North Atlantic Oceauo, as the greatest reliable depths recorded 

 do not exceed 17,000 or 1 TfiOO feet. 



The general surface of the sea-bed jjresents in general to the eje, when graphi- 

 cally rendered on charts by contour lines of equal soundings, extensive plateaux 

 varied with the gentlest of undulation?. There is diversity of feature in the 

 western Pacific Ocean, where, in the large area occupied by the many groups of 

 coral islands, their interA-ening seas are cut up into deep basins or hollows, some 

 1-5,000 some 20,000 feet deep. In the northern oceans one is struck with the fact 

 that the profouuder depths in the Pacific occupy a relative place in that ocean with 

 those found in Ib.e .itlantic. Eoth abyssal areas have this too in common : the 

 maximum depths r.ie near the land ; tlie sea-surface temperature has the maximum 

 degree of heat in either ocean ; and two of the most remarkable ocean streams 

 CFlovida-Gulf and Japan) partially encompass them. 



