SILLIMAX'S INTRODUCTION. 1 1 



while it is clad in white during the remaining months of the year. 

 Even on the first day of September, (1837,) as adventurers upon 

 this Alpine mountain,* we were, both on its flanks and summit, 

 involved in a wintry tempest of congealed vapour, formed into 

 splendid groups of feathery and branching crystals, unlike to the 

 snows of the lower regions : the driving masses came in fitful gusts, 

 veiling in a white cloud all objects far and near ; but breaking, occa- 

 sionally, to admit a flood of solar light, and render visible this 

 hoary pinnacle, and the deep gorges and valleys of the neighbouring 

 groups of mountains. 



The mountains of Essex County, State of New York, between 

 Lake Champlain and the St. Lawrence, approach the White Moun- 

 tains in altitude, but none are permanently snow-clad. 



Mountains of Central Europe. — It is otherwise in Europe, where 

 the grand central group of Mont Blanc, and the various Alpine 

 mountains, rise far into the region of perpetual congelation ; and 

 Mont Blanc would pierce that region even at the equator. Thus 

 is provided an eternal storehouse of ice and snow, over whose 

 wintry surface the winds, rendered heavier by contact, glide into 

 the valleys and plains of the countries at their feet, and thus temper 

 even the warm climate of Italy, preventing the extreme vicissitudes 

 which we experience. 



But these immense natural magazines have a still more important 

 relation to the irrigation of the vicinal countries. The melting of 

 the snow and ice, by the heat of summer, supplies copious streams 

 to feed the innumerable rivers that flow from these grand fountains, 

 to almost every part of continental Europe, south of the Baltic. 

 Thus the effects of drought are, in a great measure, prevented, 

 while destructive mountain-floods are of rare occurrence. 



Erom the absence of such mountains we have no permanent 

 stores of ice and snow, and, consequently, our rivers are liable to 

 extreme variations of altitude and force. The Ohio, in midsummer, 

 sometimes leaves numerous fleets aground, while occasional risings, 

 from deluging rains, swell the river to an immense flood, that spurns 

 the barrier of the banks, inundates villages and cities, and expand- 

 ing into an internal sea 3 rushes with wasting violence over the ■ 

 wide-spread meadows and farms. Eor this reason, hydraulic engi- 

 neering is in this country attended with peculiar diinculties, both 



* See Am. Jour. Science, vol. xxxiv. p. 74. 



