Page:Popular Science Monthly Volume 14.djvu/129

Rh On each side is a broadside port through which Whitehead torpedoes may be launched. The after-part below is fitted up as a torpedo workshop. The hull is divided into a number of water-tight compartments, not connected, as is the usual mode, with watertight doors, entrance being gained from the upper and main decks. The element of danger resulting from leaving the connections open in certain eventualities is thus obviated, though it is calculated that the filling of one or two of the compartments with water would not materially affect the behavior of the ship. She is to carry six second-class torpedo-boats. Four of these boats will be amidships, the chocks on which they rest running on a tramway. She will also carry a 42-feet steam launch and a 37 feet steam pinnace. The Hecla will be provided with booms and nets to protect her from an enemy's torpedoes—the booms, when not in use, lying fore and aft against the side of the ship.

Women and the Study of Science.—The medical profession in England appears to be seriously alarmed at the prospect of an invasion of its ranks by womankind. Scientific workers need have no such fears of their peculiar field being occupied by the gentler sex, if the "Cambridge Higher Local Examinations," lately held, are any index of the disposition of women-students in England toward scientific studies: only about thirty out of five hundred female students, we are informed by Nature, took the science subjects; twenty-one took botany, one failed, and three obtained distinction; twenty-six geology and physical geography, of whom two failed, and seven were distinguished; seven geology, one failed, three distinguished; nine chemistry, three failed, none distinguished. Ten of the science candidates sat at Cambridge, and among them they gained ten out of fourteen of the distinctions given. Miss E. M. Clarke, of Cambridge, was distinguished in geology, zoölogy, and botany, and passed in chemistry. Mathematics got only twenty-three candidates, of whom four failed; only two, however, were placed in the first class (being Cambridge students), and two in the second. We are glad to learn that two new subjects are to be set in the science group next year, namely, physics and physiology, the latter so much needed in all girls' schools. Also, students will be allowed to take this group without having to pass Group A (literature and history) first, although it will be required for a full certificate.

Sir Wyville Thomson on Deep-Sea Soundings.—Sir Wyville Thomson, as President of the Geographical Section of the British Association, delivered an address, at the Dublin meeting of that body, on the results of recent deep-sea sounding. He dwelt particularly on the facts of ocean circulation as developed by the Challenger Expedition. All recent observations, he said, have shown that the vast expanse of water which has its centre in the southern hemisphere is the one great ocean of the world, and the Atlantic with the Arctic Sea, and the North Pacific, are merely its northward-extending gulfs: any physical phenomena affecting obviously one portion of its area must be regarded as one-of an interdependent system of phenomena affecting the ocean as a whole. Shallow as the stratum of water forming the ocean is—a mere film in proportion to the radius of the earth—it is very definitely split up into two layers, which, so far as all questions regarding ocean-movements are concerned, are under very different conditions. At a depth varying in different parts of the world, but averaging perhaps five hundred fathoms, there exists a layer of water at a temperature of 40° Fahr., which may be regarded as a sort of neutral band separating the two layers. Above this band the temperature varies greatly over different areas, the isothermobathic lines being sometimes tolerably equally distributed, and at other times crowding together toward the surface, while beneath it the temperature almost universally sinks very slowly and with increasing slowness to a minimum at the bottom. With some reservation it may be affirmed that the trade-winds and their modifications and counter-currents are the cause of all movements in the stratum of the ocean above the neutral layer. All the vast mass of water, often upward of two thousand fathoms in thickness below the neutral band, is moving slowly to the northward; in fact, the depths of the Atlantic, the Pacific, and the Indian Ocean, are occupied by