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THE OCEAN WORLD. 
Laplace found, on astronomical consideration, that the mean depth 
of the ocean could not be more than ten thousand feet. Alexander 
von Humboldt adopts the same figures. Hr. Young attributes to the 
Atlantic a mean depth of a thousand yards, and to the Pacific, 
four thousand. Mr. Airy, the Astronomer Eoyal, has laid down a 
formula, that waves of a given breadth will travel with certain velo- 
cities at a given depth, from which it is estimated that the average 
depth of the North Pacific, between Japan and California, is two 
thousand one hundred and forty-nine fathoms, or two miles and a half. 
But these estimates fall far short of the soundings reported by navi- 
gators, in which, as we shall see, there are important and only recently 
discovered elements of error. Hu Petit Tbouars, during his scientific 
voyage in the frigate Venus, took some very remarkable soundings 
in the Southern Pacific Ocean : one, without finding bottom at two 
thousand four hundred and eleven fathoms; another, in the equi- 
noctial region, indicated bottom at three thousand seven hundred and 
ninety. 
In his last expedition, in search of a north-west passage, Captain 
Eoss found soundings at five thousand fathoms Lieutenant Walsh, 
of the American Navy, reports a cast of the deep-sea lead, not far from 
the American coast, at thirty-four thousand feet without bottom. 
Lieutenant Berryman reported another unsuccessful attempt to fathom 
mid ocean with a line thirty-nine thousand feet in length. Captain 
Henman, of H. M. S. Herald, reported bottom in the South Atlantic 
at the depth of forty-six thousand feet ; and Lieutenant J. P. Parker, 
of the United States frigate Congress, on attempting soundings near 
the same region, let go his plummet, after it had run out a line fifty 
thousand feet long, as though bottom had not been reached. We 
have the authority of Lieutenant Maury for saying, however, that 
“ there are no such depths as these.” The under-currents of the deep 
sea have power to take the line out long after the plummet has 
ceased to sink, and it was before this fact was discovered that these 
great soundings were reported. It has also been discovered that 
the line, once dragged down into the depths of the ocean, runs out 
unceasingly. This difficulty was finally overcome by the ingenuity of 
Midshipman Brooke. Under the judicious patronage of the Secretary to 
the United States Navy, Mr. Brooke invented the simple and ingenious 
apparatus (Fig. 1), by which soundings are now made, in a manner 
