Vegetable Stattcks . 37 
caufe of it 5 <viz> . they frequently obferve 
(efpecially with the refle&ing 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 denfity may very proba- 
bly, either acquire fuch a fealding heat from 
the Sun, as will fcorch what plants they 
touch, efpecially the more tender : an effed 
which the gardiners about London have too 
often found to their coft, when they have 
incautioufly put bell-glafies over their Col- 
lyflowers early in a frofty 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 fealding vapor, which burnt 
and killed the plants. Or perhaps, the up- 
per or lower furface of thefe tranlparent fe- , 
parate flying volumes of vapors may, among 
the many forms they revolve into, fome times 
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 (hall fall on: And fome« 
times alfo, parts of the more hardy plants 
D 3 and 
