The distribution of temperature with depth affords a natural and satisfactory explanation of the phenomenon, and renders entirely superfluous any assumption of extraordinary lightness in the water.  The true reason why the bodies of the drowned do not rise to the surface is evidently owing to the fact that when they sink into water which is only 4 deg.  Cent. (7.2 deg.  Fah.) above the freezing temperature, the gases usually generated by decomposition are not produced in the intestines; in other words, at this low temperature the bodies do not become inflated, and therefore do not rise to the surface.  The same phenomenon would doubtless occur in any other body of fresh water under similar physical conditions.[2]

[Footnote 2:  It should be noted that since 1874 there have been remarkably few deaths from drowning in Lake Tahoe, and that the major cases of those referred to by Dr. LeConte were of workmen and others who were generally under the influence of intoxicants.]

(5.) Transparency of the Water.  All visitors to this beautiful Lake are struck with the extraordinary transparency of the water.  At a depth of 15 to 20 meters (49.21 to 65.62 feet), every object on the bottom—­on a calm sunny day—­is seen with the greatest distinctness.  On the 6th of September, 1873, the writer executed a series of experiments with the view of testing the transparency of the water.  A number of other experiments were made August 28 and 29, under less favorable conditions.  By securing a white object of considerable size—­a horizontally adjusted dinner-plate about 9.5 inches in diameter—­to the sounding-line, it was ascertained that (at noon) it was plainly visible at a vertical depth of 33 meters, or 108.27 English feet.  It must be recollected that the light reaching the eye from such submerged objects must have traversed a thickness of water equal to at least twice the measured depth; in the above case, it must have been at least 66 meters, or 216.54 feet.  Furthermore, when it is considered that the amount of light regularly reflected from such a surface as that of a dinner-plate, under large angles of incidence in relation to the surface, is known to be a very small fraction of the incident beam (probably not exceeding three or four per cent.), it is evident that solar light must penetrate to vastly greater depths in these pellucid waters.

Moreover, it is quite certain that if the experiments in relation to the depths corresponding to the limit of visibility of the submerged white disk had been executed in winter instead of summer, much larger numbers would have been obtained.  For it is now well ascertained, by means of the researches of Dr. F.A.  Forel of Lausanne, that the waters of Alpine lakes are decidedly more transparent in winter than in summer.  Indeed, it is reasonable