CLIMATE of RUSSIA. 217 



at the firfi; obflacle it meets with in its courfe down the river, 

 (as at the bar a little below the city of Peterfburg) accumulates 

 fo as to form one uniform fheet to appearance, for many miles 

 above the obftacle^ compofed of a number of large thick flakes, 

 which the fevere frofl: that commonly prevails about that time, 

 almofl: inftantly cements together, although the fame degree of 

 froft is much inadequate to the power of congealing the naked 

 furface of the running river. By this oeconomy of nature, al- 

 though the northern countries are much interfedted by large 

 and rapid rivers, which, from the floating ice, do not admit of 

 Handing bridges, ftill the communication is feldom interrupted 

 for twenty-four hours, as they fliut up with a degree of thick- 

 nefs fufGcient to bear the weight of a man almofl: immediately, 

 and heavy burdens in a few days. 



Thichiefs and other Phenomena of the Ice. 



By February, our ice has acquired the aftonifhing thicknefs 

 of about three quarters of an Englifh yard, and, what is equally 

 aftonifliing, it has loft not above a third of it, when become fo 

 weak, at the breaking up of the rivers, as not to fupport the 

 weight of a dog. At this period, I have paid particular atten- 

 tion to its appearances, and found the mafs compofed of a 

 number of long folid cryflals, refembling, in fome meafure, 

 the pipes of an organ, about half a yard long, but almofl: 

 without adhefion, fo that the mafs feems to have loft little but 

 the cementing principle, (if 1 may be allowed the expreflion) 

 which bound thofe cryftals together ; inftead of its being re-; 

 duced, according to the common opinion, to a pellicle, by the 

 aftion of the fun and water on its upper and under furfaces, 

 which any one may convince himfelf is a vulgar prejudice, by 

 fimple infpedtion of a piece of the floating ice on the breaking 

 up of the Neva, which, although funk fo deep in the water as 



Vol. II. e e to 



