1822.] On the Formation of Ice in the Beds of Rivers, 187 



Article VI. 



On the Formation of Ice in the Beds of Rivers, By Thomas 

 M^Keever, MD. Assistant to the Dublin Lying-in Hospital. . 



(To the Editor of the Annals of Philosophy .) 



The numerous and formidable difficulties attendant on an 

 explanation of the principles which, under particular circum- 

 stances, occasion the deposition of an icy incrustation in the 

 beds of lakes and rivers, have induced many philosophers to 

 consider the circumstance as highly improbable ; while others 

 have gone the length of altogether denying its occurrence. We 

 are, however, no longer dependent on the casual information 

 afforded by uninformed persons for proofs of the fact ; the per- 

 sonal observations of several very eminent chemists having 

 placed its existence beyond the possibility of all doubt. 



Mr. Leslie, in a note prefixed to his very interesting work on 

 heat, tells us that many of the rivers in Siberia and Switzerland 

 are found to have their beds hned during the greater part of the 

 year with a thick crust of ice. Saussure describes a similar 

 appearance in the lake of Geneva. Mr. Garnet, in a late num- 

 ber of the Quarterly Journal of Science and of Arts, gives an 

 accurate and minute account of this singular phenomenon, and 

 mentions one place in particular where it may be observed in a 

 very striking manner. 



** On the river Wharfe, near Otiey, in the West Riding of 

 Yorkshire," Mr. G. informs us, "there is a weir or mill dam, the 

 structure of which is of hewn stone, forming a plane, inchned 

 to an angle of from 35° to 50° fronting the north, and extending 

 from W. to E. to the length of 250 or 300 yards. When the 

 wind suddenly shifts from SW. to NW. and blows with great 

 impetuosity, accompanied with severe frost, and heavy falls of 

 snow, the stone which composes the weir soon becomes 

 encrusted with ice, which increases so rapidly in thickness, as 

 in a short time to impede the course of the stream that falls over 

 it in a tolerably uniform sheet, and with considerable velocity ; 

 at the same time the wind blowing strongly from the NW. contri- 

 butes to repel the water, and freeze such as adheres to the crust 

 of the ice, when its surface comes nearly in contact with the air. 

 The consequence is, that in a short time the current is entirely 

 obstructed, and the superincumbent water forced to a higher 

 level. But as the abovementioned causes continue to act, the 

 ice is also elevated by a perpetual aggregation of particles, till 

 by a series of similar operations, an icy mound or barrier is 

 formed, so high as to force the water over the opposite shore, 

 and produce an apparent inundation. But in a short time, the 

 accumulated weight of a great many thousand cubic feet of wat^r 

 presses so strongly against the barrier as to burst a passage 



