704 REPORT — 1894. 



covers 67 millions of the 188 millions of square miles composing tHe earth's 

 surface. 



Of these 188 millions, 137 millions are sea, so that the Pacific comprises just 

 one-half of the water of the globe, and more than one-third of its whole area. 



The Northern Pacific has been estimated by Mr. John Murray to have a mean 

 depth of over 2,500 fathoms, while the Southern Pacific is credited with a little 

 under 2,400 fathoms. These fijrures are based on a number of soundings which 

 cannot be designated otherwise than very sparse. 



To give an idea of what remains to be done, I will mention that in the eastern 

 part of the Central Pacific there is an area of 10,500,000 square miles in which 

 there are only seven soundings, whilst in a long strip crossing the whole North 

 Pacific, which has an area of 2,800,000 square miles, there is no sounding at all. 

 Nevertheless, while the approximate mean depth I am mentioning may be con- 

 siderably altered as knowledge increases, we know enough to say that the Pacific is 

 generally deeper than the other oceans. The immensity, both in bulk and area, of 

 this great mass of water, is difficult to realise ; but it may assist us when we realise 

 that the whole of the land on the globe above water level, if shovelled into the 

 Pacific, would only fill one-seventh of it. 



The Indian Ocean, with an area of 25,000,000 square miles, has a mean depth, 

 according to Mr. Murray, of a little over 2,000 fathoms. This also is estimated 

 from a very insuflicient number of soundings. 



The Atlantic, by far the best sounded ocean, has an area of 31,000,000 square 

 miles, with a mean depth of about 2,200 fathoms. 



The temperature of this huge mass of water is an interesting point. 



The temperature of the surface is most important to us, as it is largely on it 

 that the climates of the difi'erent parts of the world depend. This is comparatively 

 easy to ascertain. We know so much about it that we are not likely to improve 

 on it for many years. We are quite able to understand why countries in the same 

 latitude differ so widely in their respective mean temperatures ; why fogs prevail in 

 certain localities more than others ; and how it comes about that others are subject 

 to tempestuous storms. 



On the latter point nothing has come out plainer from recent discussion than 

 the fact that areas where great differences of surface temperature of the sea 

 prevail are those in which storms are generated. 



It is a matter of observation that in the region south of Nova Scotia and New- 

 foundland many of the storms which travel over the Atlantic to this country have 

 their rise. 



An examination of surface temperature shows that in this region the variations 

 are excessive, not only from the juxtaposition of the warm water of the Gulf 

 Stream and the cold water of the Arctic current flowing southward inside of it, 

 but in the Gulf Stream itself, which is composed of streaks of warm and colder water, 

 between which differences of as much as 20° Fahr. exist. 



The same conditions exist south of the Cape of Good Hope, another well-known 

 birthplace of storms. Here the Agulhas current of about 70° Fahr. diverted bv 

 the land pours into the mass of water to the southward, colder by some 25°, and 

 the meeting-place is well known as most tempestuous. 



South-east of the Rio de la Plata is another stormy area, and here we find the 

 same abnormal variations in surface temperature. 



Yet another is found off" the north-east coast of Japan with the same conditions. 



These differences are brought about by the mingling of water carried either by 

 the flowing of a powerful current turned by the land into a mass of water of 

 different temperature, as is the case off" the Cape of Good Hope, or by the 

 uprising of lower strata of cooler water through a shallow surface stream, as 

 appears to be the case in the Gulf Stream. 



A remarkable point recently brought to light by the researches of Mr. John 

 Murray in Scotch lochs is the effect of wind on the surface temperature. It has 

 been observed that wind driving oflf a shore drifts the surface water before it. 

 This water is replaced by the readiest means, that is to say, by water from below 

 the surface rising to take its place. As the lower strata are in all cases cooler 

 than the surface, a lowering of the temperature results, and we find, in fact, that 



