244 Intelligence and Miscellaneous Articles. 



water* : and the mode of growth of ground-ice is, he believes, as 

 yet commonly regarded as an unsettled point, no opinion offered 

 having received very decisive or general assent. — Proceedings of the 

 Belfast Natural History and Philosophical Society, May 7, 1862. 



ON THE TEMPERATURE OF THE INFERIOR LAYERS OF THE AIR. 



BY M. BECQTJEREL. 



M. Becquerel has proposed in his Memoir to present a resum4 of 

 the observations made by him at the Jardin des Plantes on the 

 temperature of the air, in which he more especially tries to show 

 that this temperature in the lower layers depends, as is known, not 

 only on the terrestrial radiation and on the celestial radiation, but 

 also on the direct radiation of the sun. In commencing, he has 

 pointed out the influence of the soils, according to their nature and 

 physical condition, in raising or lowering the temperature, up to a 

 certain height, when they are heated by solar radiation, or cooled 

 by nocturnal radiation. 



If, with Schubler, the faculty which calcareous sand possesses of 

 retaining heat be called 100, a faculty which depends on its radia- 

 ting, absorbing, and conducting powers, we have — 



For siliceous sand 95*6 



For arable calcareous soil 74'5 



For argillaceous soil 68*4 



For garden earth 64*8 



For humus 49*0 



As humus has only half the power of calcareous sand, it cools in 

 less time than the latter. The size of the parts ought to be 

 taken into account : other things being equal, the siliceous and cal- 

 careous sands, as compared with equal volumes of different argilla- 

 ceous or calcareous earths in fine powder, of humus, of arable land, 

 and of garden earth, are the soils which appear to conduct heat 

 least. Hence during night in summer, sandy soils retain a higher 

 temperature than other earths. 



A soil covered with siliceous pebbles cools even more slowly than 

 siliceous sands ; hence for viniculture it is better than cretaceous or 

 argillaceous soils, in which the maturity of the grape is more slowly 

 effected. 



As these soils, once heated by the sun's rays, do not cool in the 

 same time, they do not act equally by radiation on the surrounding 

 air, so that at a given time the temperature of the air is not the 

 same for the same height above each of them ; it remains for a 

 longer time higher in a pebbly soil than in a calcareous or argilla- 

 ceous one. 



Hence in the same latitude, in the same conditions as regards pro- 

 tection, in places not very distant, and the soil of which is not the same, 



* See Professor Faraday's paper in Phil. Mag. S. 4. vol. xxi. p. 146 ; 

 and Professor Thomson's paper in the same Journal, vol. xxiii. p. 40/. 



