Page:Popular Science Monthly Volume 17.djvu/875

Rh hue of the skin, he has found that many were accustomed to take less than the usual average quantity of drink. In such cases he would prescribe an increased quantity of drink, with beneficial effects in increased perspiration, and the decrease or disappearance of the unpleasant symptoms. The waste of tissue-changes in the system passes into the blood, and leaves the system only in solution. This, Dr. Webber maintains, can not take place unless enough water is taken. Further, "water taken with the food favors digestion; when taken into the stomach a part is absorbed by the gastric vessels, carrying with it the soluble constituents of the food. So much as is not immediately absorbed assists in softening and breaking up the larger particles of food, and thus aids in the gastric digestion by facilitating the action of the gastric fluids." It also makes it easier to keep the bowels regular. In estimating the quantity of water to be taken daily, we should remember that water is excreted by the lungs and skin, as well as by the kidneys, and that much food contains water. Hence the amount required must vary slightly with the activity of the skin and the character of the food. Dalton states that the average amount is about fifty-two ounces, or 3·38 pints, or the equivalent of eight or nine coffee-cups of drink.

Temperature of the Breath.—Mr. R. E. Dudgeon has been trying some experiments on the temperature of the breath, and infers from the results that it is considerably higher than has generally been stated, and that it is variable. First, on rising in the morning, having ascertained the temperature of his body as shown by the thermometer in the axilla and mouth to be normal—about 98° he wrapped the thermometer tightly in a silk handkerchief and breathed upon it. In five minutes it indicated 106·2. At 7, after a brief walking exercise, and when he had eaten nothing but a spoonful of boiled rice, and drunk only half a glass of water and a mouthful of ginger beer, his breath raised the mercury to 107°. Immediately after a dinner at which only water was drunk, a temperature of 108° was shown. At other times the thermometer would not rise, under apparently the same conditions, higher than 102° to 105°. He can suggest no way of accounting for these indications otherwise than by admitting that they show the actual temperature of the breath as it issues from the lungs. "If so," says Mr. Dudgeon, "it is by the breath that the system gets rid of its superfluous caloric." The experiments seem to show that the temperature obtained from the breath is higher when the surrounding air is warm than when it is cold, indicating possibly that more heat is passed off by the breath when less can escape from the general surface of the body.

The Ancient Outlet of Lake Bonneville.—The name of "Lake Bonneville" has been applied to a great body of water which formerly covered the desert basins of Utah, of which the most conspicuous vestiges are its shore-lines. It is known from them that the ancient water-surface was more than ten times as great as that of the Great Salt Lake, and that the ancient level of the water was about one thousand feet above the modern level. The point at which the waters of this lake were discharged is still undetermined. Mr. G. K. Gilbert maintained, in the "American Journal of Science" for April, 1878, that the point of overflow was Red Rock Pass, Idaho, at the north end of Cache Valley; that the discharging stream descended through Marsh Valley, and thence continuously to the Pacific Ocean; and that, flowing over soft material at first, it gradually excavated at the pass a channel more than three hundred feet deep, and lowered the level of the lake by the same amount. Dr. A. C. Peale controverted Mr. Gilbert's conclusion in a subsequent number of the "Journal," and held that the original altitude of the Red Rock Pass was considerably below the highest level of Lake Bonneville; that the original shore-line exists in Marsh Valley, at the north end of the pass, as it does in Cache Valley at the south; and that the real point of discharge, when the water stood at the Bonneville level, was about forty-five miles north of Red Rock Pass. Mr. Gilbert has, within a few months, revisited Marsh Valley and Red Rock Pass, and other points near the former supposed outlet of the lake, and gives in the May number of the "Journal"