366 General Notices. 



square miles, it will be found that it would occupy upwards of 800 botanists 

 20 years to collect the principal riches of this country." (Maimers Botanic 

 Garden, June, 1837.) 



The Geography of Evergreen Trees. — " In the northern hemisphere, 

 especially in Northern Europe, evergreen trees, as well as shrubs, follow more 

 or less the sea coast,- and in southern Europe, where all the countries, 

 by their peculiar configuration, are surrounded by the sea, we have a great 

 predominance of these vegetable forms. In the southern hemisphere, on the 

 contrary, the appearance of evergreen trees and shrubs is quite an unusual 

 phenomenon ; perhaps such vegetable productions stand in more intimate con- 

 nexion than we suppose with the predominating influence of the sea. Here, 

 it is not only the subtropical zone, not only the warmer portion of the tem- 

 perate zone, which corresponds to our southern Europe, but we find this form 

 of trees with evergreen leaves extending even to Magellan's Straits, and beyond 

 them ; and our tender-leaved box of northern Europe corresponds to the ever- 

 green box trees of South America, the southern pai-ts of New Holland, Van 

 Diemen's Land, New Zealand, &:c." (Meyer on the Distribution of Vegetation 

 on the greatest Heights of the llimalayali and Upiier Peru, as quoted in Jameson^ s 

 Journal, July, 1837, p. 40.) 



Effect of Forests on the Size of River Currents. — M. Boussingault, in a memoir 

 recently presented to the Academy of Sciences at Paris, has endeavoured to 

 show the effects which the clearing away of forests has upon the force and 

 abundance of the river streams in a country. He thinks that the current of 

 water diminishes in proportion as the clearings extend; and was led to take 

 this view from observations made in America, especially in the lake of Taca- 

 rio-na or Valencia, in Venezuela, which has no outlet. This lake, in fact, di- 

 minished in depth as fast as the forests were grubbed up ; but as soon as, on 

 account of political troubles, the grubbing up ceased, the waters began to 

 assume their primitive level. Similar results have been furnished by the Lake 

 of Ubate, in New Granada, and even by those of Switzerland. 



M. Boussingault also thinks that clearing away the forests has a direct 

 tendency to diminish the quantity of rain. In the provinces of San Buenaven- 

 tura, of Choco, and of Esmeralda, which are situated to the south of Panama, 

 and where rains are almost continual, the soil is covered with thick forests ; 

 whilst towards Paita, beyond Tumbez, the forests have disappeared, and rains 

 may be said to be unknown. This want of rain is in like manner observed in 

 all the country near the desert of Sechara, and even to Lima; yet these two 

 countries enjoy the same temperature, they present nearly the same surface, 

 and have a like position relatively to the mountains. 



M. Arago remarks that a contrary result has been observed at Viviers, in 

 the department of Ardeche, where the quantity of rain fallen has augmented 

 since the clearing of forests from the country. 



On the other hand, M. Deveze of Chabriol has come to the conclusion, 

 from the examination of several historical documents, that in the department 

 of Cantal, in the environs of Saint Fleur, there has been an abatement of tem- 

 perature since the disappearance of the forests. For example, from the records 

 of the 13th and 14th centuries, it is proved that at this period the vine was 

 cultivated on the slope of the hill of Saint Fleur, and this culture will not 

 succeed at present. The chestnut has also disappeared from many "of the 

 cantons where it formerly flourished ; and many villages situated near the 

 summits of mountains have been abandoned. It is also remarked that, in this 

 country, many streams have been dried up in consequence of the clearing of 

 the forests. (UE'cho du Monde Savant, May 3. 1837.) 



Amber has been recently discovered by some German philosophers to be 

 " nothing else than an indurated resin, dei'ived from various trees of the 

 family of the Confferge ; which resin is found in a like condition in all zones, 

 because its usual original depositories (viz. beds of bi'own coal) have been 

 formed almost every where under similar circumstances. (Jameson's Journal, 

 July, 1837, p. 173.) 



