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Page:Popular Science Monthly Volume 32.djvu/497

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THE MOON AND THE WEATHER.

examination of weather registers kept by his grandfather, his father, and himself, extending over nearly eighty years, that nineteen times out of twenty a new moon on Saturday was followed by twenty days of rain and wind. It is not many weather sayings that enjoy the supporting testimony of a sober scientific investigation, and that circumstance, together with the general acceptance in which the saying is held, entitles it to special consideration.

Could we reduce the occurence of a Saturday moon to any form of periodicity—that is to say, were the accident of the new moon falling on a Saturday to recur at regular intervals—we should have some ground for at least provisionally admitting the truth of the rule, since we know that many weather phenomena are roughly periodical (though the periodicity is often completely masked by the disturbing operation of local influences), and it might so happen that this weather period coincided with that of the Saturday moon. The "cold snaps" in May» for example, recur periodically; and a cause for the phenomenon has been found in the passage of dense meteor flights between the sun and the earth, the meteors intercepting a portion of his heat. But the Saturday moon is not exactly periodical. In 1881 not a single new moon fell on a Saturday. In 1883 there were three conjunctions so distinguished. This year there are two. What sort of weather period can we imagine guilty of such eccentricities? Of course, had the adage referred to a particular Saturday moon it would have been different. The new moon falls on the same day again after a lapse of about nineteen years (a circumstance that gave rise to the Metonic cycle), and the rule would then have meant that a period of wet and windy weather occurred at a certain season every nineteen years—a notion in striking accordance with a favorite cycle of the cycle hunters. No such interpretation is possible, however, and we are obliged to include this much-respected saying in the category of idle superstitions.

We come now to the more edifying class of lunar weather notions—those that have a real physical basis. And it may not be out of place to repeat here that the writers who so emphatically and unreservedly denounce the moon and weather idea a vulgar superstition overstep the limits of scientific truth. So far as any influence of the kind we have been considering is concerned, they are quite right. The moon exerts no influence upon our atmosphere strong enough, by comparison with the other influences at work, to produce a marked correspondence between the lunar and atmospheric phenomena. Of that we are certain. Let us, therefore, belabor the false doctrine upon which the preceding and many similar notions are founded with all our might. But because the moon certainly is not a dominant factor in our weather, it does not follow that we are justified in denying to it an influence of any kind. And the results of sundry investigations have been such as to render it prudent to regard the existence of some physical connection between the two as at least an open question. Atmos-