VOL. XXXV.] VHILOSOPHICAL TRANSACTIONS. IQl 



Having thus determined the heights of the mountains of Swisserland from 

 barometrical observation, Dr. S. adds a few general observations on the natural 

 history of that country, arising from the height of its mountains. And of the 

 lakes, of which there are several, and very remarkable ones, about the borders 

 of Swisserland. The ascent of the mountains of Swisserland being so very 

 sudden and quick, the rivers, which arise in these mountains, rushing down, 

 in consequence of so quick a descent, with great force and impetuosity, they 

 would often overflow their banks, and cause frequent inundations in the flat 

 countries, if this impetuosity was not in great measure broken, and their waters 

 disposed to a more gentle descent; which is effectually done by those great 

 receptacles of water, the lakes, which are besides of infinite use to the inha- 

 bitants around them, supplying them with plenty of fish for their sustenance, 

 and enriching them by the facility with which commerce may be carried on over 

 them. 



Again, the extreme smallness of the Alpine plants is another striking obser- 

 vation : as they become less and less, in proportion as the mountains, on which 

 they grow, rise higher. Whether this be owing to the sharpness and purity of 

 the Alpine air, or the decreasing pressure of the atmosphere, which is far less 

 upon mountains than in valleys and lower countries, or to a want of a sufficient 

 quantity of subterraneous heat, to push the nourishment into the roots and 

 vessels of the plants, or rather to a joint concurrence of these and other causes, 

 would require a more leisurely consideration. The thing itself is an indisputable 

 matter of fact, and it extends also to trees and shrubs, which become smaller 

 as they grow higher. Nay, what is still more remarkable, no trees will grow 

 beyond a certain height, which is the reason why the tops of mountains appear 

 so bare and naked, if viewed at a distance, though a curious traveller shall not 

 fail meeting upon their rich pastures with an agreeable variety of beautiful 

 plants. The height, where the trees cease to grow, has been found, by baro- 

 metrical observations, to be nearly the same in divers parts of Swisserland. 

 Otherwise, the smallness of the Alpine plants is abundantly compensated by 

 the richness of their virtues. 



Again, the mountains are much more abrupt and steep, and the precipices 

 greater, to the south than to the north, and westwards than eastwards. Many 

 instances of this might be given in particular mountains in Swisserland, as the 

 Gemmi, the Mons Fractus, &c. ; but it is also evidendy true with regard to the 

 whole. Those are the highest mountains which separate Vallesia, the canton 

 of Uri, and the several leagues of the Orisons, from Savoy, Piedmont, and the 

 Tyrol, which lie to the south, or south-east. Those very countries are, as it 

 were, one continued set of high mountains, quite to the Mediterranean sea, 

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