16T 



Sometimes there is a kind of hollow clouds, full of 

 luiil or snow. During the continuance of these the 

 heat is extreme, since by such condensation they re- 

 flect more strongly. By these likewise those blasts 

 may be produced, as well as by the reflection of dense 

 Vapours, 



The Sun-flower being tender, if the sun rises clear, 

 faces to (he east. The sun continuing to shine, at 

 noon it faces to the south, and at six in the evening 

 to the west. The cause is, that side of the stem 

 which is next the sun, perspires the most, and thereby 

 shrinks. 



u What degree of heat will plants bear ?" The 

 common temperate point in the thermometer is eigh- 

 teen degrees. The external heat of a human body, 

 will raise it to fifty-four degrees. Very hot sun-shine 

 will raise it to eighty- eight. Plants endure a conside- 

 rably greater heat than this, near the line, for some 

 hours a day. But the hanging of the leaves of many 

 of tin m bhews, they could not long subsist under it. 



The winter htat is from the freezing point to ten 

 degrees ; the vernal and autumnal from ten to twenty. 

 The May and June heat is from seventeen to thirty, 

 in \f hic.'i the generality of plants ilouns'i best. The 

 heat of July is in the shade, about thirty. eight de- 

 grees ; in the sun shine, at noon, about (ifty. The 

 heat of a hot bed, when too hot for plants, is eighty- 

 five or more, and near this us tJ.o heat of the blood in 

 hiah fevers. Tne due heat of ,i hot bed is fifty. six 

 degrees, and the same heat hate lies egi<s. 



A continual steam is ascending during the summer, 

 the sun. beams giving (he moisture ot the eartii, at 

 two feet depth, a brisk, undulating motion, which 

 rarefied by heat, ascends in the form of vapours. And 

 the vigour of warm and confined vapour (such as is 

 that which is two or three feet deep in the earth) 

 ir.ust be great, and pt not rate the roots with some 

 vigour, as we may reasonably suppose from the vast 

 forre of con titled vapour in the engine for raising 

 wuter by lire. 



