In Page 253, he says, that in ascending above the Level of the Clouds, he found the Air sharp, cold and piercing: and the Wind blew strong from South West, and West South West: so that the Wind blew towards the Mountain from three different Points at least, viz. the Trade Wind, from North East below the Clouds; just above them, from South West: and still higher, a fresh Gale, from West.
“The Air on the Top of the Pike was thin, cold, piercing; and of a dry parching Nature, like the South Easterly Winds which I have felt in the great Desert of Africa, or the Levanters in the Mediterranean: or even not unlike those dry easterly Winds which are frequent in the Northern Parts of Europe, in clear Weather, in the Months of March or April,” Page 257.
This dry Wind answers to the Eknèfiai (before mentioned) i. e. Wind descending from the clouds.
Glas further observes (Page 250) that the Clouds, in fine Weather, descend gradually towards Evening, and rest on the Woods till Morning: when they re-ascend, and remain suspended above them, till the succeeding Evening.
Here then a nocturnal Depression of the Atmosphere is obvious. But this Appearance will not prove that the Air does not descend below the Level of the Clouds: for, tho’ the Clouds descend with the Air; Vapour-Air, of which they are composed, becomes transparent both by Dissolution, in a warmer Stratum, and Proximity to the Earth, as before mentioned.
Conclusion drawn from the above, applicable to Balloons.
268. From the Variety of Winds experienced at different Heights, not only on Teneriffe, but in different Places; it is plain, that if Balloons can be made durable and Air-tight; they may be wasted between the Tropics by an East or West Current at Pleasure: and also throu’out the Globe; the Occasion being made, in some Respect, subservient to the Time.[79]
