338 CONJECTURES concErnine 
torial expence, are likely to be the places moft liable to 
{pouts. ‘ 
In the next place lexpedt it will be granted that the air is 
much colder in the upper regions, and of confequence fpe- 
cifically heavier than that near the furface, by which 
when there are little or no differing motions of the air, 
(i. e. winds) in or about the region of the clouds, particular 
{pots of air and vapour in the cloud, may be difpofed to 
defcend, and, when fo, will take very aptly a particular ~ 
channel downwards. ‘Thefe things being granted what is 
of a like kind will readily be fo difpofed too, as when the 
atmofphere is full of vapours condenfing into clouds, this 
condenfation may be quicker in one place than in another, 
which by the acquired cold will become more weighty 
and prefs moft ina particular point. Thus it may defcend 
through the more rarified and yielding fubjacent region, the 
firft drops piercing and making a channel may facilitate the 
defcent of the vapour, till it puts on what Stuart calls a 
{word-like appearance. The agitation caufed by defcend- 
ing will accelerate condenfation, which together with the 
drops pafling through the vapour in this channel, may at 
every {top in the paflage be wafting the vapour, by taking 
it up into leffer mafles of water till it ends in a point, 
which it will in this cafe naturally do, becaufe the {wifteft 
motion down is in the center of the pointing body. 
Such a {pout may increafe fo as to form maffes of wa- 
ter, the fubftance of the cloud, all obftacles removed, paf- 
fing down in greater abundance, and ftill more fwiftly 
condenfing; or it may prefently ceafe when it has but juft 
appeared, or inftead of this, make, as it were, feveral at- 
tempts for completing a fpout, the vapour teat advancing 
and retiring alternately, but which finally fail, without 
producing effe&. Thus it has done, as it feems, when 
the cloud has not had fufficient fupplies for it to fucceed 
in a complete and opaque {pout. Such are the appear- 
ances of Mr. Stuart’s figures, &c. The obliquity of the 
pointing 
