Page:Popular Science Monthly Volume 10.djvu/67

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years. During the month of October, 1873, the average height of the barometric column was 757.1 millimetres, and for the same month in 1854 it was 757.2 millimetres; the barometric mean for the five days between the 22d and the 28th was, in 1873, 750.7 millimetres, and in 1854, 748.7 millimetres; the minimum was reached, in 1873, on October 23d, and in 1854 on October 25th, being in the former case 734.9 millimetres, and in the latter, 734.5 millimetres. In 1873 the maximum was reached in the evening of October 28th—773.7 millimetres, and in 1854 at noon of the 28th—774.9 millimetres. The weather was also the same in both years from the 3d to the 7th, and from the 21st to the 27th of October. From the 5th to the 7th there were frequent and heavy falls of rain; on the 7th, in 1873, and on the 5th, in 1854, there were violent thunder-storms. On both years from the 21st to the 25th the atmosphere was in a state of violent disturbance, the barometric column being very low. And here we may state that there was new moon at 11 a. m. on October 21, 1873, and at 9 p. m. on October 21, 1854; that in 1873 the southern lunistice occurred at 10 p. m. of the 26th, and in 1854 at 9 p. m. of the 26th; and that the moon's declination at the time was about 27° south.

Further, from the 13th to the 16th of November, 1873, the distribution of atmospheric pressure over Europe and the state of the weather were similar to what they were on the same days in 1854. The fearful ravages wrought by the storms in the Black Sea on the days between the 13th and the 16th of November,1854 (the Crimean War being then in progress), will render those days ever memorable. The numerous shipwrecks in the sea of Azof, and the loss of English and French war-ships in the Black Sea on the 13th and 14th, showed how desirable and necessary a thing it was that there should be found some means of warning seafarers of the approach of storms. It was these disasters which gave occasion to the establishment of storm-signals. From the 13th to the 15th of November, 1873, after a period of calm, with high barometer over the greater part of Northwestern Europe, we find succeeding a similar barometric minimum, and a storm area advancing across the Mediterranean toward the Black Sea.

At any given point of the earth's surface the state of the weather always depends on the prevailing air-currents. The annual and the secular periodic changes of the oceanic and the atmospheric currents are repeated in the weather-changes. And on the phenomena which, however imperfectly, establish this periodicity, is based the universal belief that the moon has an influence on the weather. The researches and calculations which have been made by meteorologists to determine the periodicity of weather phenomena, and the influence of the moon upon the latter, have hitherto been fruitless, and this simply because the observations of single stations only have been taken into account. From observations made at one point it is impossible to