Baron Leopold Von Budi on the Subtropical Zone. 129 



rent is this liberal manner of seeing the interests of science, from 

 the narrow and despicable jealousies of which the history of 

 literature and science presents but too many examples ! If we 

 have thought it our duty to mention this event as an honourable 

 fact in the history of botany, we also loVe to make it known as 

 a fact honourable to the human heart, — as a proof of the progress 

 of civilization, and of the intimate connection which is every day 

 becoming more firmly established among enlightened nations. 



On the Subtropical Zone. By Baron Leopold Von Buch. 



±HE Tropical Zone oi the earth is, in a physical point of view, 

 characterized by the tropical rains. These rains follow the 

 course of the sun, and always occur where the sun is in the 

 zenith of the place. During the time of the greatest declination 

 no rain falls. 



In temperate climates^ on the contrary, the weather is clear 

 and bright when the sun stands highest, but it rains when he has 

 removed to a considerable distance. These latter rains appear 

 with winds, which blow from the equator or from low latitudes 

 towards the poles, probably by reason of the cooling of the 

 npper equatorial trade-winds, which, in higher latitudes, touch 

 from above the earth, and flow over it for a considerable length, 

 I have endeavoured to prove these conjectures by an appeal to 

 facts *. The transition from the one zone into the other, is 

 made by an intermediate one, which can be accurately distin- 

 guished from the two formed by physical phenomena. I be- 

 lieve it deserves the name of Subtropical Zone. Humboldt, 

 after making known the observations of Boussingault, in Santa Fe 

 de Bogota, remarked, that the progressive decrease and increase 

 of the medium heights of the barometer in different months, 

 which Boussingault was inclined to derive from the greater or 

 lesser distance of the sun, occurs again not only on a greater 

 scale at Rio Janeiro, but also only in opposite months at the Ha- 

 vannah and Macao. It is, in truth, a general phenomenon, which 

 depends on general causes, from those, namely, that occasion 

 the trade-winds. The followii^g Table shews the phenomena. 



"In my observations on the climate of the Canaries, in the Memoirs of 

 the Berlin Academy for the year 1820. 



A PKir, — JUNE 1830. i 



