116 



KEMARKS ON SURFACE TEMPERATURE. 



of the influence of the seasonal temperature of the earth at greater depths, 

 to which the same principles apply. 



This point is well brought out in the following statements of results of 

 the observations of Mr. Whitley at Penarth in the summer, and of my own 

 later in the year : — 



Here while the slight cooling power of gravel is in accordance with Mr. 

 Glaisher's estimate, the minimum of the mould falls below that on the 

 grass, in strong divergence from his rule. 



My own observations in the following December give very different 

 results, the surface temperature on grass being distinctly lower than that 

 on garden mould : — 



It may be noticed that the higher temperature of the mould is most 

 marked in the coldest nights. 



