Professor Gordon on the Temperature of the Earth. 



reference to the influences of heat, branches and roots mutually exchange 

 the parts they play in the economy of the plant in each half of the year. 

 If the growth of the parts be really a function of the temperature, we 

 should arrive at the conclusion, that the roots develop themselves more 

 powerfully in winter than in summer. This may be compared to a 

 branch which is taken in winter from a tree in the open air into a hot- 

 house, and which lives there a nurseling of fortune, as if it had no con- 

 nexion with the dead trunk outside. 



The Upsala experiments bring out, with peculiar distinctness, how the 

 rapid increase of temperature of the surface in spring is retarded at the 

 greater depths; and from them we learn, too, how tlie deeper layers always 

 indicate this rapid increase, if in any given year it has been observed 

 earlier in the layers above. 



In winter, on the other hand, the under layers are much less affected 

 by anomalies. Dove explains it in this way: that the snow-covering, 

 then probably on the ground, being a bad conductor, prevents the soil 

 from participating in the many changes of tho atmosphere. The snow- 

 covering has a twofold influence, inasmuch as it hinders the radiation 

 from the ground, on the one hand, and as it prevents communication of 

 heat by contact with the air, on the other. 



The relative circumstances of the parts of plants out of the soil being 

 tho same, the mean temperature of the whole plant will be so much 

 the lower in summer, and so much the higlier in winter, the deeper its 

 roots penetrate into the variable stratum. Plants with roots going 

 deep into the soil, live, therefore, in circumstances approximating more 

 to what is termed a sea-climate, than do those whose roots penetrate less 

 deeply. 



The following tables, from Quetelet's observations (on the south side of 

 the Observatory at Brussels) for depths of 4, 16, 24, 32, and 40 inches 

 depth, from May, 1840, to December, 1844, as arranged by Herr Dove, 

 perfectly illustrate this. 



Table I. a. — Temperatures at Depths. 



Surface. 4 Inches. 16 Inches. '24 Inches. 32 Inches. 40 Inches. 



Jan 122 127 202 316. 



Feb 184 1-78 244 316. 



March,... 6-61 535 567 5*49 529. 



April,.... 10-07 8-07 8-54 8-25. 



May, 1518 1348 1378 1298. 



June,.... 17*25 1588 1643 1604. 



July, 1709 15-99 16-79 16-28. 



Aug 17-70 16-89 17*57 1727. 



Sept 13-56 15-21 1631 1642. 



Oct 976 9-89 1127 1207. 



Nov. 5-74 631 7'41 834. 



Dec 1-73 2-63 402 512. 



