belief that sleeping in the moonlight, especially if the Moon is full, induces insanity. A belief in the connection between the Moon and insanity was formerly very widely diffused, as witness our word lunacy. Farmers believe that the Moon exercises a certain influence over vegetation, and that beans, for instance, should be planted when the Moon is light, and potatoes when it is dark. What this really means is not very obvious, but presumably that beans should be planted about full moon, and potatoes when the Moon is new.
Many people believe that a change in the weather will come at or about the time of a change in the Moon. Since the Moon changes every seven and a half days, every change in the weather must come within four days of a change in the Moon, and half the changes will necessarily come within two days of a lunar change. We must not confuse this superstition with the real but ill-defined seven-day period of the weather, which is a genuine phenomenon, and holds true to a certain extent. Thus if one Sunday is stormy, there is a certain probability that the several Sundays following may have the same sort of weather. This phenomenon is probably due to terrestrial causes, and has nothing whatever to do with the Moon.
Another superstition is that if the horns of the new moon will hold water it will be a dry month; if they are so tipped that the water will run out, it will be rainy. It should be stated, however, that nearly as many people hold the reverse view. Both views are erroneous. The line joining the Moon's horns is always perpendicular to the direction of the Sun, and therefore depends merely on the place of the Moon in its orbit. It is sometimes said that the full moon clears away clouds. It is a fact that it is often cloudy at moonrise and that as the Moon rises higher the clouds disappear. The explanation, however, is that the full moon always rises about sunset. It is on the whole more cloudy at sunset than it is later in the evening. The clouds therefore clear away in any case, but when the Moon is full we are more likely to notice this fact than under other circumstances. A large number of proverbs relating to the Moon were collected by the United States Signal Service, and published in 1883, under the title "Weather Proverbs." To these I must refer those who are especially interested in this matter, discussing now merely a few influences of the Moon for which there really appears to be some foundation in fact.
It has been said that thunderstorms are influenced by the Moon. Doctor Hann refers to this in his " Lehrbuch der Meteorologie," page 662. He cites two series of German
