468 Meteorology. 



Art. V. Meteorology/, 



Rules for the Weather. — A wet summer is always followed by a frosty 

 winter, but it happens occasionally that the cold extends no farther. Two 

 remarkable instances of this occurred in 1807-8 and 1813-14. With these 

 exceptions, every frosty winter has been followed by a cold summer. 



The true cause of cold, or rather the direct cause, is to be found in the 

 winter excess of west wind, every winter with excess of west wind being 

 followed by a cold summer; and if there is no cold before, or during a first 

 excess, then a second excess of west wind in winter occasions a still colder 

 summer than the first. It also appears, by repeated experience, that cold 

 does not extend to more than two years at a time. 



Again, if the winter excess of east wind be great, in the first instance, 

 the winters will be mild, and followed by mild summers: while the summer 

 excess of east wind is itself, in the first instance, always mild; but uniformly 

 followed by cold winters and cold summers, which continue, more or less, 

 for one or two years, according to circumstances. {Mackenzie^ Syst. of the 

 Weather.) 



Electricity of the Winds. — In the Mediterranean Mr. Black ascertained, 

 by numerous observations, that winds or currents of vapour of some con- 

 tinuance from an extent of sea, are negatively charged with electricity ; 

 while those from the land, especially from hilly countries, are relatively in 

 a positive condition. When opposite winds, such as north and south, are 

 differently charged with electricity and meet, a transfer of the electric matter 

 is always the consequence. {Journ. in Mediternan.) 



Air for Analysis. — To collect air for the purpose of analysis, instead of 

 emptying a bottle filled with water, as is usually done, M. Gaultry de Clau- 

 bry employs a saturated solution of sulphate of magnesia in the same way, 

 {Annales de C/iimie, vol. xxxvii. p. 380.) 



Malaria the Cause of Sun-stroke. — Dr. M'Cnlloch is of opinion that the 

 sun-stroke, or coup-de-soleil, as it is called, which proves bO often fatal in 

 hot climates, and is commonly attributed to the sun, is probably nothing 

 more than the access of marsh fever, caused by exposure to malaria on 

 the previous evening or morning. It is not, however, denied, that expo- 

 sure to a burning vertical sun may not produce inflammation of the brain, 

 and prove rapidly fatal. {Brande's Journ., vii.) 



Analysis, of the South-west Wind. — This wind consists of' air flowing 

 from the south, and seeming occasionally absorbed at its arrival at the more 

 northern latitudes. It has a real direction from the west, owing to its not 

 having lost in its journey the greater velocity it had acquired from the 

 earth's surface whence it came. — J. R. 



Halo round the Sun. — The last time I was gj; Resley, I witnessed a 

 colourless halo round the sun, precisely like those usually seen surrounding 

 the moon, except that the diameter of the circle seemed larger than those 

 of lunar haloes usually are. It continued for a quarter of an hour or so. I 

 had never witnessed a solar halo before, and was in hopes I should have, for 

 once, seen a parhelion, or mock sun; but no such phenomenon occurred, 

 the halo gradually dying away. — John Thompson. Hidl, July 20. 1829. 



Rules for determining the Temf)erature of a Country. — The fact that a 

 degree of latitude is equal to a degree of Fahrenheit, and that 400 ft. of 

 elevation is equal, also, to a degree of Fahrenheit, is original and curious, 

 and will go far to assist us in determining the clime of any country. 

 {Amer. Quart. Rev., March 1829, p. 174.) 



