Wat ER SB. OU TS. 107 
electric capacity* ; and when heated and rarefied to fome 
certain degree will give way, as obferved above, to the 
denfer air, now proportionably difpofed to flow in from 
all quarters without the limits of the calm. 
When once this ftagnated air, efpecially if of any great 
extent, becomes fpecifically lighter than the furrounding 
air, and fufficiently rare to be fupplanted by it; the latter 
will, of courfe, fet it from every fide in horizontal currents ; 
which will flow, either dire@ly, or obliquely, towards one 
point, in or near the centre of the becalmed reyion afore- 
faid ; the obliquities of which currents will depend upon 
the directions and velocities of the winds, or currents of 
air which might previoufly have taken place in the fur- 
rounding regions. When thefe currents arrive at the cen- 
tre of their mutual convergency, all the {tagnated and ra- 
refied air which was before incumbent upon the calm fur- 
face of the fea, will have been expelled and forced higher 
upinto theatmofphere; upon which thefe currents, by their 
mutual concourfe in one place, will exceflively croud each 
other, as obferved above, wherever it happens, driving the 
central air upwards with a violent blaft; which, fhould 
the currents fet in obliquely, and fo converge with a {piral 
motion towards the centre of their mutual concourfe, 
would afcend as through the fcrew of Archimedes, or the 
worm of a cork-fcrew, to both of which navigators have 
likened thefe {pouts: Otherwife it would rife through a 
ftrait, narrow funnel, as inarticles five and fix above; which 
if filled with any opaque matter would become vilible, and 
at a diftance would refemble a {peaking trumpet with the 
fmall end downwards, in which form the water {pout fre- 
quently appears. In the former cafe a whirlwind round 
about the centre would undoubtedly be the confequence ; 
and in either, a water {pout would probably be produced. 
O32 For 
* See Theory of Lightening, &c. page 8r. 
+ We fhall in the fequel fee abundant reafon to conclude with doctor Franflin and others, 
that water fpouts at fea and whirlwinds on the land (fome fpecies of them at leaft) are produc- 
ed by the fame caufes. 
