PEBIODICITY OF RAINY AND DRY YEARS.

Otago Daily Times, Issue 6149, 24 October 1881, Page 3

PEBIODICITY OF RAINY AND DRY YEARS.

M. do Parvillo has published in tho Journal dos Debats a papor on tho temperature of- tho present j'ear, which at Paris has risen to a hoight exceeding all previous authentic records. On July sth, at the Observatory in the Park of St. Maur, tho centigrade thermometer registered 350 degrees, and on July 15th, 37- 8 degrees. Tho highest temporaturo previously recorded during the present century was 3f1"75 degrees, on July 31st, 1803. Higher temperatures have been recorded, but their authenticity has been questioned. Thus, Cassini has rocorded 40 degrees for August 17th, 1701; but it is believed that the true temperaturo was only 3G'BS degrees. So, also, the temperature set down by Messier of 39 degrees in 1703, and 40 degrees in 176 D, are attributed to errors of observation, and should bo corrected to 3G'U and 375 degrees respectively. M. de Parvillo passes on to ask whether tho dryncss of tho present summer could have been foreseen, and lie answers in the alh'niiatho. Having- referred to the influence uf the solar action on the atmosphere, he says:—"A very long series of observations has also shown that tho moon, which passes every month froni one hemisphere to, the other, inlluenocs the direction of the great .atmospheric currents. The changes in those currents, in consequence of the prevailing moisture or dryness, are intimately connected with the relative position for tho time being of the sun and Moon. The distance of tho moon from the equator —that is, the inclination of the moon's path to the plane of tho equator—varies every year, passing from a maximum to a minimum limit; and tho meteorological character of a series of years appears to be mainly dependent upon tho change of inclination when those extreme limits have been touched. Observations prove that tho rainy years, the cold winters, and hot summers return periodically, and coincide with certain declinations of the moon. In our latitudes tho rainy years occur when tho moon's declination has touched its extreme limits of 21, 20, or 18 degrees respectively. They are separated from each other usually by periods of about three years and then six years. The following table traces backwards this connection between the rainy years and tho moon's declination: — Greatest Declina- Greatest doclination of moon. tion of moon. Kainy Rainy year Do". year. Deif. '1879 .. ..28 ISI9 .. .. 2S IS7G .. .. '28 ISIO .. .. 20 1572 .. .. 20 1810 .. .. IS ISCO .. .. 18 180-1 .. .. 20 3859 .. .. 2S ISOO .. ..23 1850 .. ..28 170S .. ..28 1553 .. .. 20 1792 .. .. 18 1819 .. .. 18 1787 .. .. 20 IS3G .. .. 20 1785 .. .. 28 1527 .. ..IS 1753 2S ..20 IS2I .. ..20 The severe winters as a rulo coincide, at least within a year, with tho same declinations :—IS79, IS'75, 1871,1807,1859, 1857,1803, 1840, 1837, 1835, 1830, 1829, 1522, 1819, 1818, 1815, 1815, 1812, 1800, 1804, 1801,1798, 1792, 1788, 1785, 1782. Tho dry summers come naturally in tho middlo of the period which divides two wet years, thus—lß74, ISG'J, 1803, 1857, 1854, IS-19, 1812, 1832, 1825. Applying tho rulo which this experience suggests to the summer of 1881, we find that the next wet year ought to coincide with tho declination of 18deg., therefore with the year ISI4, as tho last was 1879 with tho declination of 2Gdog. Consequently the dry summers should como about the middle of the intervening period between those two years—that is, they should bo 1881 and 1882. It might therefore have been foreseen that, beginning with 18S0, wo wero proceeding towards a maximum of dryness."— London Times.