DECEMBER. 337 



smiling spring, or the glorious summer, with their thousand 

 gladdening accompaniments, that make our blood dance, and 

 our hearts leap ! 



F. But it would not do for summer to last always. 

 Nature requires a season of comparative rest, as well as of 

 action. Important purposes in vegetation are fulfilled in 

 winter, which, though they are unseen, are not unfelt in their 

 consequences ; juices are elaborated and modified ; recently 

 developed parts acquire strength and consistency ; and plants 

 are prepared to shoot out fresh buds, the rudiments of an*- 

 other verdure. Yet winter is not altogether cheerless ; by 

 searching we may yet find a few subjects worthy of investi- 

 gation, and capable of affording amusement and instruction 

 to the mind ; nature is never barren of lessons of wisdom, to 

 him who possesses a mind willing to receive them. 



C. The wind blows keen, although, when we set out, 

 the thermometer indicated rather a mild temperature. How 

 is this ? why shall one day to our senses be quite warm, 

 and the next keenly cold, though the mercury stands at 

 the same degree on both ? I know it is caused by the pre- 

 sence or absence of wind, but I do not see why the wind 

 should have so sensible an effect on our feelings, and yet 

 make no corresponding alteration in the state of the thermo- 

 meter. 



F. Our senses do not give us a true estimate of the real 

 temperature of the atmosphere. Cold is not a positive qua- 

 lity : it is merely a negation, the absence of heat : the sen- 

 sation of cold is caused by the animal heat being abstracted 

 from the surface of our bodies faster than it can be generated 

 internally. It is the property of heat to equalize itself by 

 passing out of one body which has more, into another in 

 contact with it, which has less, until the temperature of both 

 is alike: but some substances abstract heat more rapidly 

 than others, whence they are called good conductors of heat. 



Q 



