may, doubtless, be found in the high specific heat of water, the great depth of the Lake, and in the agitation of its waters by the strong winds of winter.  In relation to the influence of depth, it is sufficient to remark that, before the conditions preceding congelation can obtain, the whole mass of water—­embracing a stratum of 250 meters in thickness—­must be cooled down to 4 deg.  Cent.; for this must occur before the vertical circulation is arrested and the colder water floats on the surface.  In consequence of the great specific heat of water, to cool such a mass of the liquid through an average temperature of 8 deg.  Cent, requires a long time, and the cold weather is over before it is accomplished.  In the shallower portions, the surface of the water may reach the temperature of congelation, but the agitations due to the action of strong winds soon breaks up the thin pellicle of ice, which is quickly melted by the heat generated by the mechanical action of the waves.  Nevertheless, in shallow and detached portions of the Lake, which are sheltered from the action of winds and waves—­as in Emerald Bay—­ice several inches in thickness is sometimes formed.

[Illustration:  Lily Lake]

[Illustration:  Cave Rock, Lake Tahoe]

[Illustration:  Pyramid Peak and Lake of the Woods]

[Illustration:  Clouds Over the Mountain, Lake Tahoe]

(4.) Why Bodies of the Drowned do not Rise.  A number of persons have been drowned in Lake Tahoe—­some fourteen between 1860 and 1874—­and it is the uniform testimony of the residents, that in no case, where the accident occurred in deep water, were the bodies ever recovered.  This striking fact has caused wonder-seekers to propound the most extraordinary theories to account for it.  Thus one of them says, “The water of the Lake is purity itself, but on account of the highly rarified state of the air it is not very buoyant, and swimmers find some little fatigue; or, in other words, they are compelled to keep swimming all the time they are in the water; and objects which float easily in other water sink here like lead.”  Again he says, “Not a thing ever floats on the surface of this Lake, save and except the boats which ply upon it.”

It is scarcely necessary to remark that it is impossible that the diminution of atmospheric pressure, due to an elevation of 6250 feet (1905 meters) above the sea-level, could sensibly affect the density of the water.  In fact, the coefficient of compressibility of this liquid is so small that the withdrawal of the above indicated amount of pressure (about one-fifth of an atmosphere) would not lower its density more than one hundred-thousandth part!  The truth is, that the specific gravity is not lower than that of any other fresh water of equal purity and corresponding temperature.  It is not less buoyant nor more difficult to swim in than any other fresh water; and consequently the fact that the bodies of the drowned do not