of the Atmofpbhere. 113 
fpheric tides produced by heat, as the gentle wind obferved 
at the times of high water in the ocean, even during wea- 
ther in othef refpects calm, proceeds from an atmofpheric 
tide produced by attraétion. 
The difficulty of breathing which people experience in the 
torrid zone, under an atmolpheric tide, arifing from heat, 
mutt be afcribed as much to a rarefaction of the air thereby 
occafioned, as to the heat itfelf. A like effect, in regard to 
breathing, is perceived on high mountains; which however 
arifes from the thinnefs of the air on thefe eminences, for 
here the heat can haye no part in the rarefaétion. 
It happens fometimes, in warm countries, that during the 
atmofpheric tides, the heat and rarefaction of the air increafe 
to fuch a degree that they create fcorching and fuffocating 
winds, known under the name of Sc/anos ;, the violence of 
which proceeds fo far fometimes, that they deftroy on the 
‘fpot thofe who are immediately expofed to them. Abun- 
dant and horrid inftances of this circumftance are quoted by 
the Abbé Richard in his Natural Hiftory of the Air and 
Meteors which have occurred in the Defarts of Arabia, in 
e neighbourhood of the Perfian Gulph, and other places. 
Befides thefe /olanos, it is obferved alfo, fometimes, that 
“the wind fuddenly ruthes from all quarters to that point 
where the air is moft rarefied, which occafions ftorms and 
urricanes in that part by the mutual fhock of the air and 
the vapours ftreaming in all directions towards one centre, 
“and the winds then blow backwards again from this point to 
‘every quarter of the heavens till the equilibrium is reftored. 
This effe&t, fo natural and common, has long aftonifhed thofe 
who never employed themfelves in endeavouring to difcover 
the caufe. 
In the laft place, there is good reafon for conjecturing that 
‘the fame phyfical caufes which produce the different atmo- 
‘fpheric tides, with their confequences, contribute alfo to . 
‘thange the weather and temperature, and to produce at the 
fame time a great many other meteorological phenomena. 
‘ 
VoL. V. Q Il. On 
