rendered barter and commerce possible, but its apparently botmdless 

 immensity probably first suggested the idea of infinity, and thus 

 led to the conception of an Omnipotent and Omniscient Being. To 

 the ocean we are indebted for the first naturaHsts, in the persons 

 of the primitive fishermen, who cast their nets in the creeks of the 

 Cyclades, and the ancient Phoenician sailors were undoubtedly the 

 first of marine engineers. The ocean covers no less than three- 

 quarters, or, to be quite correct, eight-elevenths of the surface of 

 the earth, indeed if the earth were of one uniform level it would be 

 entirely submerged in the sea to a depth of 600 feet. The average 

 depth of the sea is about 2,000 feet, ranging from a mean of 180 

 feet in the Baltic to 14,500 feet in the Atlantic and 16,400 feet in 

 the Pacific. One reads sometimes of vast abysses and unfathom- 

 able depths of ocean, but the soundings taken by Maury and others 

 prove that there exists nowhere a greater depth than five miles. 

 It is true that a lead line may run out for 40,000 or 60,000 feet, or, 

 indeed, indifinitely, without touching bottom, but this is because 

 the undercurrents of the deep sea have power to bear the line off 

 longitudinally, long after the plummet has ceased to sink. The 

 ocean is continuous all over the earth, and practically maintains the 

 same level, contrary to the belief held not long since that the 

 Mediterranean and some other inland seas were of a higher level 

 than the open ocean. The bulk of the ocean is so great that it has 

 been calculated if all the enormous basins which it now fills were 

 empty, it would require 40,000 years for all the rivers of the earth 

 to re-fill them. 



Sea water, when pure, is the most perfectly transparent of all 

 fluids, as I daresay many of you have found out to your cost when 

 you have stepped into one of the transparent pools often found 

 among the rocks at low water. This transparency is of course 

 relative, not absolute, and ceases entirely at a certain depth. Many 

 experiments have been made by Professor Tyndall, Pere Secchi, 

 and others, to measure the extent of this transparency by sinking 

 white plates and various coloured discs attached to a string 

 beneath the surface of the sea, and noting the depth at which they 

 ceased to be visible. It was found that a white disc 12ft. in 

 diameter appeared light green at the depth of a few feet, then blue 

 green, later dark blue, and finally disappeared from view at a depth 

 of 126 feet. Discs of yellow or brown disappeared much more 

 quickly. These experiments were made in the transparent waters 

 of the Mediterranean, and under a bright sunny sky, i.e., under 

 the most favourable circumstances. Now, as the bottom of the 

 sea is never absolutely white, and if it were, could not possibly be 

 seen at a greater depth than about 130 to 140 feet, it is difficult 

 to believe the wonderful stories told by travellers of ocean bottoms 



