Vegetable Statkh. 37 



caufe of it; viz. they frequently obferve 

 ( efpecially with the reflecting Telefcopes ) 

 fmall feparate portions of pellucid vapors 

 floating in the air; which tho' not vifible to 

 the naked eye, are yet confiderably denfer 

 than the circumambient air : And vapors of 

 fuch a degree of denfny may very proba- 

 bly, either acquire fuch a fcalding heat from 

 the Sun, as will fcorch what plants they 

 touch, efpecially the more tender : an effecT: 

 which the gardeners about London have too 

 often found to their coft, when they have 

 incautioufly put bell-glaffes over their col- 

 lyflowers early in a frofly morning, before 

 the dew was evaporated off them ; which 

 dew being raifed by the Sun's warmth, and 

 confined within the glafs, did there form a 

 denfe tranfparent fcalding vapor, which burnt 

 and killed the plants. Or perhaps, the up- 

 per or lower furface of thefe tranfparent fe- 

 parate flying volumes of vapors may, among 

 the many forms they revolve into, fometimes 

 approach fo near to a hemifphere, or hemi- 

 cylinder, as thereby to make the Sun-beams 

 converge enough, often to fcorch the more 

 tender plants they fhall fall on : And fome- 

 times alfo, parts of the more hardy plants 



D 3 and 



