Mr. Hinds on Climate, ^c, — Temperature. 311 



elytra there are three or four longitudinal rows of tubercles of a 

 larger size : on the suture and at the commencemeut of the apical 

 third of the elytra is a tubercle which is provided with a tuft of 

 small hairs : the body beneath is pitchy red ; the upper parts are of 

 a dull red colour. In some specimens small scattered green scales 

 are observable on the thorax and elytra, especially on the sides of 

 the former, and at the base and on the sides of the latter. 



[To be continued.] 



XXXVI. — The Physical Agents of Temperature, Humidity, 

 Light, and Soil, considered as developing Climate, and in con- 

 nexion with Geographic Botany. By Richard Brinsley 

 Hinds, Esq., Surgeon R.N. 



[Continued from p. 1S9.] 



Hitherto our attention has been chiefly directed to the tem- 

 perature of the air, under the influence of various circum- 

 stances which regulate the amount. The direct heating power 

 of the sun's rays, or radiation, has not been noticed, though 

 their action on the vegetable kingdom is often very important. 

 As vegetation under usual circumstances is fully exposed to 

 the effects of the seasons, the conditions to which it is liable, 

 from the presence or absence of the sun, become a subject of 

 important inquiiy. Two different results follow radiation : 

 the first is an increase in the sensible heat during the period 

 of the sun's rays above the horizon ; the second is a decrease 

 of the same, due to a transfer of heat during the night from 

 the earth, by what is called terrestrial radiation. By this the 

 temperature around vegetation is capable of being very con- 

 siderably reduced. 



I. Daily observation shows us the very great difference 

 between the impression made on our feelings by the tempe- 

 rature of the shade and the sun's rays. The fact ascertained, 

 it was next necessary to discover W'hether it obeyed any re- 

 gularity in its relation to the temperature conferred on the 

 air by the sun, and whether the progression of the seasons, 

 time of the day, or the latitude, influenced this relation. The 

 laws of its influence over the surface of the globe are now 

 generally determined, and they become another confirmation 

 of that omnipotent foresight by which the conditions of om* 

 nature were so distributed, that where at first view the abs- 

 ence of an agent would convey a momentary impression of 

 error or confusion, a little inspection will display a new agent 

 compensating for the absence of the other. 



Its relations in different latitudes are not perhaps what would 



