Page:Popular Science Monthly Volume 86.djvu/138

134 nervous temperament often affirm that they have forebodings of coming thunderstorms or of rainy spells through a temporary disturbance of their neural equilibrium. Physiologically considered, either from the point of view of man or of the lower animals, these fore-warnings, often verified, have some basis for their existence. The secret of the explanation probably lies in the fact that all weather changes occur in cycles—that is, a more or less constant order of events accompanying every change. With the summer thunderstorm this cycle usually consists of the following: rising temperature and humidity, pressure oscillations, decreasing winds, increasing potential of atmospheric electricity, thickening clouds and consequent growing darkness, distant lightning, rumbling thunder, the lightning growing more vivid and the thunder louder and louder as the storm approaches, a squall of wind coming from the direction of the storm itself, accompanied by a marked fall in temperature, inconstant humidity, large drops of rain, followed by a downpour, often accompanied by hail. Another cycle, covering a considerably longer period of time, is recognized as a precedent of the rains of a barometric depression. Men differ greatly from the lower animals in their sensitiveness to these various stages, and even different individuals, whether in the higher or in the lower orders of animal life, show wide divergence in this respect. As a result, sensitive persons and certain animals feel a coming change because for them the change has already begun, they feel the rising humidity or the changing pressure before others, and they are, in fact, simply changes usually precedent to the larger changes observed by all. However, one or more of these changes may occur without reference to the various other changes, thus explaining why the premonitions are sometimes amiss. But cycles of this nature occur so frequently that traditions of a fair degree of reliability have arisen. It might be added that most of the reliable proverbs based upon the behavior of animals are ultimately concerned with changes of humidity. To such changes certain animals appear to be super-sensitive, while most men are phlegmatic in this respect.

That rain has resulted from the concussions attending the old-fashioned celebration of Independence Day (July 4) or during great battles, particularly those of the Civil War, has long been a popular belief. Even before gunpowder was used for military purposes it was held that rain was produced by the clashing of swords and armor in physical combat. The explanation offered was to the effect that widespread concussions caused the small vapor particles floating in the air to coalesce to form raindrops, the dust and smoke furnishing the necessary nuclei of condensation. Records obtained in all parts of the United States and covering long periods of years fail to show that precipitation is heavier or more frequent upon July 4 or 5 than it is upon July 2 or 3. Moreover, so far as the records are available, the rain