Interest derived from the Stud^ of the Wefither, 177 



The atmosphere, being a fluid of different densities, must 

 necessarily be almost always in motion; it is expanded by 

 evaporations of water raised into it, and decreased in volume 

 when these are withdrawn. One, perhaps never-ceasing, mo- 

 tion it must necessarily have, though not usually perceptible 

 near the surface of the earth ; viz. currents of cold air from 

 the poles to the equator, and contrary currents above, of 

 warmer and lighter air, from the equator to the poles. 



Art. XIIT. On the Art of deriving Interest from the Study of the 

 Weather. By Mr. A. Gorrie, C.M.H.S. 



There are fevf sciences more imperfectly understood, and, 

 I believe, there are few more generally interesting, than me- 

 teorology, as far as it relates to temperature, moisture of the 

 atmosphere, and their effects on vegetation as well as on the 

 health and comfort of the human species. So generally oper- 

 ative are these effects on the animal spirits, that every man is 

 more or less a meteorologist ; even the lower animals, in many 

 instances, afford sufficient evidence of their being instinct- 

 ively prognosticators of approaching changes in the state of 

 the atmosphere ; vegetables too, by the contraction and expan- 

 sion of their foliage and flowers, have in the absence of more 

 scientific criteria been referred to for the same indication ; 

 and it may not be altogether out of place here to submit a 

 few of these popular indications in the shape of queries, con- 

 ceiving that the Magazine of Natural History is the proper 

 channel through which their solution may be obtained. 



Why is the awn of the wild oat and of the sw^eet-scented 

 spring grass more straight when the hygrometer indicates sa- 

 turation, than when the air contains less moisture ? 



Why do the convolvulus, the anemone, and anagallis shut up 

 their flowers, and many species of trefoil shut up their leaves, 

 and why does the Porlier« hygrometra contract its foliage, 

 before rainy weather ? 



Why does the mole send up earth, why do earthworms 

 appear on the earth's surface, and why are toads seen to 

 move more than usual, when dry weather is to be succeeded 

 by rain ? 



Why are the summits of some lofty mountains covered 

 with a cap of mist, when there is none in the adjacent valleys, 

 about twenty-four hours before rain ? 



