degrees farther fouth, and in a much more genial climate, have 

 hitherto proved unfuccefsful. The olive tree cannot poflibly be 

 cultivated in the interior of Afia or America, though the latitude 

 be in other refpeds favourable, nor is it fruitful when excluded 

 from the fea breezes *. 



The caufe of this may be that near the fea the temperature is 

 more regular than within land, and fudden changes are perhaps un- 

 fa vQurable to evergreens : for we always find thofe with broad leaves- 

 grow bed in the fliade, and thofe with narrow leaves on elevated- 

 places, in both of which Situations the temperature is more 

 regular than in open expofures or confined vallies. And we 

 may often obferve plants growing on a fomewhat elevated fi- 

 tuation, if fheltered from ftrong winds, lefs hurt in a fevere 

 winter, than others in low warm and fheltered places. For 

 vapour being raifed in fuch places during the day, produces a 

 greater degree of cold by cOndenfation and evaporation in the 

 night, than is experienced in other places where the coldnefs of 

 the air prevented the rife of vapour during the day. From every 

 obfervation it appears, that thofe plants which have the leaft fap 

 in winter, or whofe fap is of a refinous or oily nature, fuffer leaft 

 from cold, and that the principal caufe of deftrudion is the veffels 

 being burfl by the freezing of the fap. The hoar-froft, which is 

 always moft abundant in vales, tends in a great degree to promote 



this ; 



* See Saint Pierre's Studies of Nature, tranflated by HuiiteT, Vol. I. page 50"^. 

 Dublin Edition. 



