204 ‘PROGRESS OF ATMOSPHERIC 
Humboldt states, that he enters into these details 
because Europeans usually confine themselves to a 
description of the impressions made on their minds 
by the solemn spectacle of a tropical thunder-storm ; 
and because, in a country where the year is divided 
into two great seasons of drought and rain, it is in- 
teresting to trace the transition from the one to the 
other. In the valleys of Aragua, he had from the 
18th of February observed clouds forming in the 
evening, and in the beginning of March the ac- 
cumulation of vesicular vapours became visible. 
Flashes of lightning were seen in the south, and 
at sunset Volta’s electrometer regularly display- 
ed positive indications, the separation of the pith- 
balls being from three to four lines. After the 26th 
of the latter month, the electrical equilibrium of the 
atmosphere seemed broken, although the hygrome- 
ter still denoted great dryness. 
The following is an account of the atmospheric 
phenomena in the inland districts to the east of the 
cordilleras of Merida and New Grenada, in the 
Llanos of Venezuela, and the Rio Meta, from the 
fourth to the tenth degree of north latitude, where- 
ever the rains continue from May to October, and 
consequently include the period of the greatest heat, 
which is in July and August :—“ Nothing can equal 
the purity of the atmosphere from December to Fe- 
bruary. The sky is then constantly without clouds, 
and should one appear, it is a phenomenon that 
occupies all the attention of the inhabitants. The 
breeze from the east and north-east blows with vio- 
lence. As it always carries with it air of the same 
temperature, the vapours cannot become visible 
through refrigeration. ‘Towards the end of Febru- 
