Page:Popular Science Monthly Volume 18.djvu/734

716 of the light is wasted. M. Clémandot aims by his process to make all the light available for illumination. It is based on the principle which governs the diffusion of the light of the sun. This is effected by vapors floating between us and the sun, which distribute the light equally without stopping more than a very small proportion of it. To imitate these vapors he uses a solid substance, but in a condition so attenuated as to be, for practical purposes, almost the same as vaporous. It is glass, spun into threads one hundred and seventy-five times finer than a hair, or forty-five times finer than the finest silk fiber, with which he surrounds the light with a double envelope. His glass-fleeces are put into a lantern constructed especially for the purpose, so as to exclude dust, the glasses of which may be given any desired degree of opacity, and any color, including those colors which will neutralize the injurious properties of the electric light. The apparatus can be adapted to any of the systems of electrical lighting.

William Lassell.—William Lassell, LL. D., F. R. S., the famous astronomer and maker of telescopes, died October 5th, in the eighty-second year of his age. His name is closely associated with the history of the reflecting telescope. About 1820, not having sufficient means to enable him to buy expensive instruments, he began to construct reflecting telescopes for himself, beginning with a Newtonian and a Gregorian telescope of seven-inch aperture, with which he succeeded so well that he was encouraged to make a Newtonian instrument of nine inch aperture. In 1844 he began an instrument of two feet aperture and twenty feet focal length, in the making of which he introduced many improvements over the similar instrument of the Earl of Rosse. With this instrument he discovered the satellite of Neptune in 1846, the eighth satellite of Saturn, simultaneously with Professor Bond, in the United States, in 1848, and two satellites in addition to the two already known, of Uranus, in 1851. He afterward made an instrument of four-feet aperture and thirty-seven feet focus, which he set up at Malta, and with which he made numerous observations of nebulae and planets, besides preparing a catalogue of six hundred new nebulæ discovered at Malta. His latest recorded work was the construction of an improved form of machine for polishing large telescopic mirrors, which is described in the "Transactions of the Royal Society" for 1874.

Climatology of Europe.—The climate of Western Europe is ameliorated by the warmth of the Gulf Stream in winter, and by the neighborhood of the ocean in summer, and approaches what is called an insular climate. In Eastern Europe these modifying influences cease to be felt, and the climate gradually assumes a continental character, with greater differences of temperature, colder winters and warmer summers. The differences in the summer temperatures of the eastern and western regions are less marked than those in the winter temperatures, and amount at most to about 27°. For the greater part of the continent the difference in the temperature of July is not more than about 18°. The mildest summers are felt in Ireland and Norway, and the hottest in Southeastern Europe. The difference is perceptible between places in corresponding latitudes in the southeast and southwest. Thus, Syracuse is 7° and Sebastopol is 5° warmer in July than Lisbon and Oporto. A similar difference, but less in extent, appears in going eastward along the northern parallels. The differences in the winter temperatures of the several parts of the continent are much more marked than are those of the summer temperatures. The mildest winters are felt along the Mediterranean coast and in the Iberian Peninsula, where the mean temperature in January is from 16° to 19°. The next mildest are those of the western coast of France and the southern coast of England and Ireland. The winters of western Scotland and the Orkney and Faroe Islands are milder than those of Berlin and Milan; those of the Arctic coasts of Scandinavia than those of the Gulf of Bothnia, as is shown by the fact that the Arctic fiords of Norway, even as far as North Cape, are not frozen, while the Gulf of Bothnia is regularly frozen in winter. In Russia the January temperature diminishes as we go east, so that, while it is about 24° at Warsaw, it is reduced to 4° at Uralsk. The highest annual mean temperature, the