THE POPULAR SCIENCE MONTHLY.
��powder lost all its suli)lmr, but did not take fire. With a lamp inclosed in a bell glass the three explosive substances were decom- posed in twenty minutes. ^Yater, with which the interval was tilled, came to the boiling point in fifteen minutes. It was ob- served even when the beginning of an igni- tion of the explosives was determined, the flame was not sure to be propagated, unless the substance had been previously wanned. On the other hand, a derivation of weak re- sistance, produced between the two conduct- ors of a lamp, determines a strong flame, ca- pable of igniting all combustible substances. A lamp may be broken by a shock, by overheating, or by some unknown cause. If only a crack is formed, the air getting with- in causes the filament of incandescent carbon to burn up in a very short time. If the lamp bursts or has a hole made in it, the danger is greater, and may cause the ignition of ex- plosive gases, but not of fulmicotton or dry powder. It is not safe, therefore, to con- clude that an accident is absolutely impos- sible.
The Whirlpools of Charybdis and Scylla.
— Charybdis and Scylla, the whirlpools of which much'was fabled in classical antiquity, are situated in the strait of Messina, between Sicily and Italian Apulia. Although they were a great terror to ancient navigators, they are in reality rather small affairs, and it is difficult to determine their exact posi- tions. The whirlpool of Scylla is situated at the foot of the cliffs on which is the little city of that name, which are hollowed out into caverns. The circulation of the waves in these grottoes produces, in times of heavy seas, a sound like the barking of a dog. Charybdis is near the port of Messina, nine marine miles from Scylla. Although it was reported unfathomable, it is, according to Spallanzani's measurements, not more than five hundred feet deep, and is therefore far from being the deepest spot in the Mediter- ranean. It is difficult to comprehend why the ancients should have had such a terror of sailing between these two eddies so far apart, but the task of explaining the riddle has been undertaken by the engineer, M. Keller. Observations made by him at Mes- sina show that the currents of the strait de- pend, first, on the tide, and, secondly, on the
��wind. The currents are very strong, because the tide is low in the Ionian Sea when it is high in the Tyrrhenian Sea, and vice versa. Hence, also, the formation of whirlpools at different points in the strait. These whirl- pools are energetic in proportion to the strength of the current, and when at their strongest may offer a serious danger to navi- gation. At the syzygies, with the wind from the southeast, the waters tumble from the Ionian Sea into the strait and form whirlpools north of the port of Messina; they are likewise formed near Faro, where ships at anchor are sometimes carried out to sea and borne by the current upon the rocks of Calabria, toward the point of Pezzo, a little farther away than Scylla. We may therefore suppose that the ancients meant by Charybdis these casual whirlpools near the port of Messina, and by Scylla those of Point Pezzo. Between these two points the currents are extremely rapid and strong and variable besides. Under such circumstances an inexperienced sailor might therefore have difficulty in passing the strait of Messina without falling from Charybdis into Scylla. The danger is really serious for sailing ves- sels, which were the best the ancients knew of.
Consnmption at Daios Platz. — A case is recorded by Dr. A. T. T. Wise, of Davos Platz, Switzerland, of a consumptive mani- festing serious symptoms ordered to that place for the mountain air, who began to re- gain lost ground in two weeks after his arrival, near the end of October, 1891. Pro- gression toward recovery, with gradual ex- pansion of the chest and gain in weight, was uninterrupted till February, 1892, when the physician's examination showed improvement near to recovery in every affected part. In October, 1892, the patient, having gained twenty-eight pounds in Davos, had resumed his practice of medicine, was in robust health, and presented no sign of disease except a faint, hardly perceptible expiratory harsh- ness over the left apex. The climatic ad- vantages at high altitudes in pulmonary dis- ease, as summarized by Dr. Wise, are: Dry- ness of the air and its comparative freedom from micro-organisms and atmospheric dust, entailing a lessened liability to catarrh and irritation of the bronchial tract and drying the lungs ; profusion of sunUght ; with the