126 



EARTH TEMPERATDEE. 



depth, a temperattire of 103°. " On the third of Decemher, a 

 thermometer huried a quarter of an inch deep, in contact with 

 a seedling fir of the year's planting, quite healthy, and having 

 its seed-leaves marked as follows.- — at ll"" SS"" a.m. 148-2°, at 

 Qi" 48™ p.m. 149-5°, at 1'" 34'" p.m. 149-8°, at 1^ 54™ p.m. 150-8°, 

 and at S^ 46™ p.m. 148°." Sir John Herschel observes that 

 such ohservations " go to show that at the Cape of Good Hope, 

 in the hot months, the roots of bulbous and other plants which 

 do not seek their nourishment very deep, must frequently, and, 

 indeed, habitually, attain temperatures which we can only imitate 

 in our hothouses by actually suspending over the soil plates of 

 red-hot iron. For it must be remarked, that heatiag the 

 ground /rom behw would not distribute the temperature in the 

 same way." 



Memoranda conoermng the temperature immediately below the 

 surface of th.e earth, oeoasionaUy remarked in different countries : — 



133°— 144° . ( ^'"'°r^™g ^ Edwards 



* ( and Colin. 



Often 126°— 134° .... Humboldt, Fragm. As. 

 Coarse white sand at 140°, s 



the atmosphere being [ 



84-5° 



118°— 122°; once 127°, the 



atmosphere being 91-5° 

 113° — 118° among dry ] 



grass J 



85° usual summer temp. 



one foot below surface . 

 159° under the soil of 



bulb garden 

 142° thermometer barely \ 



covered ....,; 

 Water of rice fields 113° 

 adjacent sandy soil much 

 higher ; for towards midday 

 the black sides of the boat 

 were 142-50° 



Egypt. . . 

 Tropics . . 



Oronoco . . 



France . . 

 Chile . . . 



New Grenada 



Cape of Grood 

 Hope . . 



Bermuda . . 



Lantao, Chinas: 



of a ) 



Humboldt. 



Arago, as quoted by 

 Edwards and Colin. 



Boussingault. 



Hay, in Zoudon's Gard. 

 , vi. 437. 



Herschel [MSS.). 



Col. Emmet. 



^Meyen. 



These observations seem to confirm the late Mr. Harvey's 

 suspicicJns, that the real force of the sun's rays in tropical 

 countries is still far from being ascertained. When, therefore. 



