100 



TEMPEPvATUKE OF THE EARTH IN 



ground to admit of the lubes being adjusted to the intended 

 depth, 1 and 2 feet below the surface; and when so adjusted, 

 the earth was filled in, and consolidated by watering. 



The situation in which these thermometers were placed was 

 the lawn in the Arboretum, open to the sun, and unsheltered 

 from rain. The grass was kept short, but allowed to grow 

 closely round the ground thermometers. The thermometers in- 

 dicating the maximum and minimum temperatures in the shade, 

 and which afforded the comparative data in the following tables, 

 were in the same compartment with the ground thermometers 

 and others indicating the degrees of sun-heat and radiation. The 

 whole were enclosed by a M'ire guard. 



The nature of the soil in which the ground thermometers were 

 insei'ted is a blackish loam, resting on a stratum of yellow loam. 

 The latter is pierced, however, by the common earthworm, in a 

 perpendicular direction, through to the gravel ; and by this 

 means a good drainajT^e has been effected, and is still maintained. 



