116 P aching of the Ice. 



out from Longueuil on the opposite shore. In the narrow chan- 

 nel between them, the water,, rushing with much force, producer 

 the Sault Normand,. and cooped up a little lower down by the 

 island of St. Helen and several projecting patches of trap, it forms 

 St. Mary's Current. 



The interval between St. Helen and the south shore is greater 

 thau that between it and Montreal ; but the former is so floored 

 and crossed by hard trap rooks that the St. Lawrence has as yet 

 produced but little effect in wearing them down, while in the 1 

 latter it has cut out a channel between thirty and forty feet deep, 

 through which the chief part of its waters rush with a velocity 

 equal to six miles per hour. Tt is computed that by this channel 

 alone upwards of a million of tons flow past the town every 

 minute. 



Between this point and Lake St. Peter, about fifty miles down, 

 the river has an average breadth of two miles 7 and proceeding in 

 its course with a moderate current, accelerated or retarded a little 

 according to the presence or absence of shoals, it enters the lake by 

 a multitude of channels cut through its delta, and forming a group 

 of low flat alluvial islands. 



The frosts commence about the end of November, and a margin 

 of ice of some strength soon forms along the shores of the river 

 and around every island and projecting rock in it ; and wherever 

 there is still water it is immediately cased over. Tne wind, acting. 

 on this glacial fringe, breaks off portions in various parts, and 

 these proceeding down the stream constitute a moving border on 

 the outside of the stationary one, which, as the intensity of the 

 cold increases, is continually augmented by the adherence of the 

 iee-sheets which have been coasting along it \ and as the station- 

 ary border thus robs the moving one, this still further outflanks 

 the other,, until in some part the margins from the opposite 

 shores nearly meeting,, the floating ice becomes jammed up be- 

 tween them r and a night of severe frost forms a bridge across the 

 river. The first ice-bridge below Montreal is usually formed at 

 the entrance of the river into Lake St. Peter, where the many 

 channels into which the stream is split up greatly assist the 

 process. 



As soon as this winter barrier is thrown across (generally 

 towards Christmas), it of course rapidly increases by stopping the 

 progress of the downward-floating ice, which has by this time 

 assumed a character of considerable grandeur, nearly the whole 



