PECULIAR FOG IN ICELAND. 153 



and much disregarded in works on Meteorology, I shall 

 give the opinions of some who are the principal originators 

 or at least those best known to me. To begin with 

 Edmund Halley, the astronomer, I quote from the abs- 

 tract of his paper in the ' Philosophical Transactions/ 

 The actual paper itself is not much longer, but it was not 

 at hand. 



" I have formerly attempted to explain the manner of 

 the rising of vapour by warmth, by showing that if an 

 atom of water were expanded fnto a shell or bubble so as 

 to be ten times as large in diameter as when it was water, 

 such an atom would become specifically lighter than air, 

 and rise as long as that flatus or warm spirit that first 

 separated it from the mass of water shall continue to dis- 

 tend it to the same degree ; but that warmth decreasing, 

 and the air growing cooler and so specifically lighter 

 [heavier is meant], the vapours consequently will stop at 

 a certain region of the air or else descend, which may 

 happen on several accounts, as will be seen below. Yet I 

 assert not that this is the only principle of the rise of 

 vapours and that there may not be a certain kind of 

 matter whose conatus may not be contrary to that of 

 gravity, as is evident in vegetation, wherein the tendency 

 of the sprouts is directly upwards, or against the perpen- 

 dicular. But whatever be the true cause, it is certain 

 that warmth does separate the particles of water and emit 

 them with a greater velocity as the heat is more intense, 

 as is evident in the steam of a boiling caldron, wherein, 

 likewise, the velocity of the ascent of the vapours visibly 

 decreases till they disappear, being dispersed and assimi- 

 lated into the circumambient air." — Phil. Trans, (abridged) 

 vol. iii. p. 428. 



Gottlieb Kratzenstein, candidate in Medicine at Halle, 

 obtained the prize from the Bordeaux Royal Academy of 

 Belles-Lettres, Sciences, and Arts, for his 'Theorie de 



