Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

676 A FEW REMARKS after the first few hundred fathoms, the deeper it penetrates ; if not the increased resistance to sinking, found by the weight and line? " Friction, caused bypassing through the water,"" I may be told. Can that friction be compared with the augmented tendency to sink that would be given by the continually increas- ing weight of line, if the water did not increase in density ? The pressure of the column of water over any weight, after it has been sunk some hundred fathoms, is shown by the time and exertion required to haul it up again. The operation of sounding in very deep water, with any considerable weight, occupies several hours, and a great number of men. That water is elastic has been proved by Canton's experiments as well as others : but there are familiar illustrations of this fact visible in ricochet shot, in ' ducks and drakes,' in the splashing of water, and in the rebounding of rain-drops from water. Being elastic, and the lower strata being under enormous pressure, it follows that those strata of water must be more dense than the body above them. No one doubts that the lower regions of the atmosphere are denser than the higher ; yet air is but a rarer and much more elastic fluid than water. That which takes place in air, to a great extent, may be expected to occur in a very diminished degree with water. If it were not so, why should stones be blown up, casks violently burst, or rocks suddenly torn asunder by the application of the principle usually described as the hydrostatic paradox .'' If the water were not highly compressed before the explosion takes place, would there not be a gradual yielding, a tearing asunder by degrees, instead of a sudden and violent bursting.? The object of this digression is to show that although bodies whicli are not buoyant may sink to a considerable depth, it does not follow that they must sink to the bottom. Each separate thing may sink a certain distance, in proportion to its specific gravity, and there remain. The greatest depths evei* reached by heavy weights, attached to lines, do not exceed a mile and a-half; a small distance, probably, compared with the depth of the diluvial flood. Although metals, stone, rock, or coal may have sunk deeply in