Page:Popular Science Monthly Volume 8.djvu/785

Rh of principles necessary for the development of the beet; on the contrary, the reason of the phenomenon is, that the soil is too rich in nitrogenous matters, in consequence of the liberal use of manures.

Balloons and Carrier-Pigeons.—It is related by a writer in the London Quarterly Review for July, that when Pilâtre de Rozier had descended safely to the earth, after making the first aërial voyage ever undertaken by man, Benjamin Franklin, who at the time (November 21, 1783) was in Paris, on being asked his opinion of the brothers Montgolfier's invention, replied, "A child has just been born." But hitherto its growth has been extremely slow. Nevertheless, the history of aërial navigation is full of interest, and it is well told by the writer in the Quarterly. Some of the early objections against ballooning were singular enough. Thus, it was urged that female honor and virtue would be in continual peril, if access could be had by balloons at all hours to the windows of houses! Politicians objected that, if the path of air were to be made free, all limits of property and frontiers of nations would be destroyed. As a matter of course, aërial navigation was denounced as "impious." And, when the brave Pilâtre des Rozier's balloon took fire in the air over the city of Boulogne, and he lost his life, many a one recognized herein the "hand of Providence," just as the peasant-girl, who saw a deal chair fall "from heaven," at once decided that it was a part of the household furniture of the angels. In point of fact, Gay-Lussac, who happened at the time to be overhead, had thrown the chair out of his car, to lighten his aërostat.

During the siege of Paris by the Germans, a balloon post was established in the city. At first there appeared to be innumerable obstacles in the way of this enterprise, the chief one being the difficulty of obtaining a sufficient number of aëronauts. In this strait, the aid of seafaring men resident in the city was invoked, as their training had made them familiar with operations and dangers akin to those of ballooning. From September to January, sixty-four balloons were sent off, and of these fifty-seven fulfilled their mission. The number of letters thus dispatched was 3,000,000. The writer in the Quarterly Review mentions one incident connected with these balloon voyages which seems hardly credible: On one. occasion, the crew of a balloon found themselves over the sea, out of sight of land. Seeing vessels they made signals for help, but were not answered, and one vessel fired on them. The men afterward descended to the earth in Norway.

To carry dispatches and letters into Paris, carrier-pigeons were employed. The dispatches, public and private, were first printed on pages of folio size, 16 of which were placed side by side, forming a large sheet about 54 inches long by 32 wide. This was reduced by photography to $1⁄800$ of its original area, the impression being taken on a small pellicle of collodion, two inches long and $1 1⁄4$ wide, and weighing about $3⁄4$ of a grain; each contained about 2,000 words, or 32,000 words in all, equal to about 58 pages of this magazine. Every pigeon carried twenty of these leaves, which were carefully rolled up and put in a quill. At the Government office in Paris, the quill was cut open, and the collodion leaves carefully extracted. They were then magnified by an optical apparatus, copied, and sent to their destination.

Mental Overwork.—One of the great evils of modern life, in the estimation of many eminent physicians, is mental overwork. It is asserted that affections of the heart are now more numerous than ever before, that asylums for the insane are being overcrowded, and that nervous disorders of every kind are on the increase. What are the signs which indicate impairment by overwork? This question is thus answered in the Sanitary Record: "Overwork," says the Record, "exists when the sense of energy once possessed is distinctly impaired; when it is found an effort to get through what was once a cheerful task; when what was once found comparatively easy is beginning to be felt a trial; and above all when errors or omissions, the direct outcomes of a flagging and wearied brain, commence to manifest themselves. To spur on an exhausted brain, and by application and longer hours of toil to compel the overtaxed nervous system to complete its round of duty, is one of the most disastrous and erroneous measures that can