Page:Popular Science Monthly Volume 49.djvu/155

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143
FRAGMENTS OF SCIENCE.

blowing at times over ten metres per second. "These experiments," he says, "have given the most interesting results that I have arrived at since I began." With a wind velocity of six or seven metres per second, the sailing surface of eighteen square metres carried him against the wind in a nearly horizontal direction from the top of the hill without even having to run at the start, as is generally necessary. In a stronger wind he allows himself to be simply lifted by the wind from the hilltop and sail slowly against it. As experiments have shown, the sailing path is directed strongly upward by increasing wind force, and this fact causes him sometimes to be higher in the air than he was at his original starting point. In this position his apparatus has occasionally come to a standstill; and this leads him to make the following interesting statement: "At these times I feel very certain that if I leaned a little to one side, and so described a circle, and further partook of the motion of the lifting air around me, I should sustain my position. The wind itself tends to direct this motion. I have made up my mind by means of either a stronger wind or by flapping the wings to get higher up and farther away from the hill, so that, sailing round in circles, I can follow the strong uplifting currents and have sufficient air space under and about me to complete with safety a circle, and lastly to come up against the wind again to land."



MINOR PARAGRAPHS.

In a recent report to the French Academy of Medicine, M. Henri Monod says that from January, 1895, since the knowledge of antidiphtheritic serum and its uses has been extensively diffused throughout France, the statistics have shown a marked diminution in the mortality from the disease. In the population of one hundred and eight cities in France, each having more than twenty thousand inhabitants (the only places from which the reports are sent to the central administration), during the first six months of the seven years preceding 1895 — that is, from 1888 to 1894 — the average number of deaths was twenty-six hundred and twenty-seven. During the first six months of 1895 the diminution was 65·6 per cent. This diminution is not simply continuous, but is steadily increasing, as is proved by statistics from month to month. In a little pamphlet on this subject by Dr. Welch, of the Smithsonian Institution, he says that "the study so far of the results of the treatment of over seven thousand cases of diphtheria by antitoxine demonstrates beyond all reasonable doubt that antidiphtheritic serum is a specific curative agent for diphtheria, surpassing in its efficacy all other known methods of treatment for this disease," while "the essential harmlessness of the serum has been demonstrated by over a hundred thousand injections."

An accident of considerable scientific interest recently resulted m the photographing of a meteor. On November 23d last, at about ten minutes past twelve at night, Mr. C. P. Butler, of Knightsbridge, with the intention of focusing and testing the field of a new lens, placed a quarter-plate camera on the window sill, pointed it roughly at the region near the boundaries of Perseus, Andromeda, and Aries, and exposed it for about ten minutes. Upon developing the plate, the track of a meteor was the first impression to be perceived. Confirmation of the occurrence of the meteor is given by its having been observed from the South Kensington Observatory, both the time of the fall and the estimated region of its path being identical with the above observations.

M. Berthelot, says Industries and Iron, with the view of avoiding the inaccuracy arising from the unknown or irregular expansion of the containing vessel of the gas thermometer, has recently been experimenting with a new method of measuring temperatures. He employs the varying refractive power of gases at different densities. A given refraction always corresponds to a given density, though the pressure and temperature may be different. The principle is applied by the method of interference. A luminous beam is split up into two parts, which traverse two tubes filled with the same gas, and the initial appearance of the interference fringes is noted. One of the tubes is then raised to the temperature which it is