Page:Popular Science Monthly Volume 17.djvu/591

Rh would be inexplicable, and contrary to every natural law and precedent, if it did not do so. The force of character, strength of will, clearness of mental vision, and qualities of vigor, patience, and perseverance, which constitute the secrets of success in life, are the several properties of the physical organism, compounded as it is of body and mind." A new cure is suggested, then, the "health-cure," as a remedy for adversity, which would be first personal, then hereditary in its aim, aspects, and bearing. The subject is worthy the attention of medical men and social philosophers.

Carrying a French Meridian into Africa.—Colonel Perrier furnishes a description to "La Nature" of the manner in which the French system of triangulations and the meridian lines have been extended into Algeria under his direction. The idea of establishing a geodesic connection across the Mediterranean had been entertained for more than seventy years, but it was considered doubtful, on account of the great distance from each other of the points that would have to be used in the observations, whether a correct measurement was practicable. Preparations for making the observations were begun in 1873. Four points were chosen (Mulhacen and Tetica in Spain, 11,537 feet and 676 feet above the sea, Filhaoussen and McSahiba in Algeria, 3,760 feet and 1,876 feet above the sea), which formed a quadrilateral the angles of which were all visible from each other. It was necessary, from considerations of climate and locality, to make all the observations in the latter part of the summer and the early fall. Solar reflections were to be used in the day, and the electric light at night, as signals. The solar reflections were never seen at any of the distant points, and proved a complete failure. After about twenty days of effort, the electric light was made visible at all the points, and was used successfully from the 10th of September till the 1st of October, when the first series of observations was satisfactorily completed. The calculations showed that, notwithstanding the extraordinary distances apart of the points of observation (one hundred and seventy miles), the solutions were as exact as in cases involving only a few miles. In making the astronomical projections of the points, a system of rhythmic signals, or of stated alternate flashes and eclipses of the electric light, was employed from the 5th of October to the 16th of November. It was found that these signals were susceptible of great precision, but that the personal equation could not be disregarded in observing them. This equation operated in a double sense, as related to the observation of the stars and of the signals, in each observer, and had to be ascertained by a series of special experiments instituted in the case of each person at the observatories at Paris. Practically, it was a matter of indifference to the observers whether they directed their attention to the flashes or to the eclipses of the light, but they considered the observations of the eclipses likely to be more exact. The most convenient rhythm of signals was found to be one of about two seconds, allowing one second for the flash and one second for the eclipse. The constancy of the personal equation as it related to the luminous signals was remarked, and the error to be allowed for was estimated at less than one hundredth of a second.

Mr. Fleuss's New Diving-Process.—We noticed in the March number of the "Monthly" the invention by Mr. Fleuss of a process for breathing under water, which dispenses for the most part with the cumbrous apparatus that divers have hitherto had to employ. A fuller account of the new method has been published since, in the English papers, and those features of it which were then kept secret have been disclosed. The power of breathing depends on means which are provided within the helmet worn by the diver. These means are designed to furnish a continuous supply of oxygen, and to dispose of the carbonic acid which the breather exhales. No provision is made for the nitrogen which enters into the composition of ordinary air, for this merely serves as a diluent, and is not changed or diminished in quantity by breathing; hence the nitrogen which is naturally present in the diver's lungs and in his dress when he puts it on can be used over and over again, and is amply sufficient for its purpose. The oxygen is stored in the helmet in a compressed state, and the supply is regulated by a valve which is