[BARNES] |>NCHOR-ICE FORMATION 67 



laj'ers of ice already formed there. The term anchor-ice we shall 

 use to designate all ice found attached to the bottom irrespective of 

 it-s nature of formation. Thus, frazil becomes anchor-ice .when it 

 attaches itself to the bottom. The birth of frazil is in the water 

 itself by surface cooling through wind or rapid agitation. Anchor-ice 

 may form in situ on the bed of a river, and may grow by attaching 

 to itself frazil crystals brought down by currents or by the slower pro- 

 cess of radiation. 



In the report of the Montreal Flood Commission we have the 

 terminology clearly defined and we cannot too strongly emphasize 

 the importance of adliering to this distinction for clearness of expres- 

 sion. Thus, referring to the important report published by the Com- 

 mission as early as 1888, we find the following : — " Frazil, as distin- 

 guished from Anchor-ice, is formed over the unfrozen surface above 

 and below Lachine Eapids (St. Lawrence Eiver, at Montreal) between 

 Prescott and tide water, and wherever there is sufHcient current or 

 wind agitation to prevent the formation of bordage ice." 



'W'e find that as early as 1810 writers of that time drew a distinc- 

 tion between three kinds of river ice, if we may judge from an early 

 edition of the Encyclopedia Britannica published at that date. Under 

 the article on Ice, we find the following : " Ice forms generally on 

 the surface of the water; but this, too, like the crystallization, may 

 be varied by an alteration in the circumstances. In Germany, par- 

 ticularly the northern parts of tlie country, it has been observed that 

 there are three kinds of ice. 1. That which forms on the surface. 

 2. Another kind formed in the middle of the water, resembling nuclei 

 or small hail. 3. Ground-ice, which is produced at the bottom, espe- 

 cially where there is any fibrous substance to which it may adhere. 

 This is full of cells like a wasp's nest, but less regular; and performs 

 many strange effects in bringing up very heavy bodies from the bottom, 

 by means of its inferiority in specific gravity to the water in which 

 it is formed. The ice which forms in the middle of the water rises 

 to the top, and there unites into large masses; but the formation both 

 of this and the ground-ice takes place only in violent and sudden colds, 

 where the water is shallow and the surface is disturbed in such a man- 

 ner that the congelation cannot take place. The ground-ice is very- 

 destructive to dykes and other aquatic works. In the more temperate 

 European climates these kinds of ice are not met with." 



These three kinds of ice are what we term sheet, frazil and anchor- 

 ice.' 



^ A . full discussion of the formation of the three kinds of ice will be 

 found in my " Ice Formation, with special reference to Anchor-Ice and 

 Frazil," "Wiley & Sons, New York, 1906. 



