Prof. Tyndall on Ice and Glaciers. 401 



and came from the mould in the sharply defined form sketched 

 in fig. 6. 



Fig. 6. 



I placed a small piece of ice in warm water and forced it un- 

 derneath the water by a second piece. The submerged morsel 

 was so small that the vertical pressure was almost infinitesimal. 

 It froze, notwithstanding, to the under surface of the superior 

 piece of ice. Two pieces of ice were placed in a basin of warm 

 water, and allowed to come together. They froze as soon as they 

 touched each other. The parts surrounding the place of contact 

 rapidly melted away, but the two pieces continued for a time 

 united by a narrow bridge of ice. The bridge finally melted 

 away, and the pieces were for a moment separated. But it 

 is well known that bodies which water wets, and against which 

 it rises by capillary attraction, move together when caused 

 to swim upon water. The ice morsels did so, and immedi- 

 ately regelation set in. A new bridge was formed, which in 

 its turn was dissolved, and the pieces closed up as before. Thus 

 a kind of pulsation was kept up by the two pieces of ice. They 

 touched, froze; a bridge was formed and melted, leaving an interval 

 between the pieces. Across this interval they moved, touched, 

 froze, the same process being repeated over and over again. We 

 have here the explanation of the curious fact, that when several 

 large lumps of ice are placed in warm water and allowed to touch 

 each other, regelation is maintained among them as long as they 

 remain undissolved. The final fragments may not be the one- 

 hundredth part of the original ones in size; through the process 

 of closing up just described, they incessantly lock themselves 

 together until they finally disappear. What is true of ice-frag- 

 ments in a basin of water, is also true of the ice-blocks in the 

 Margelin See ; and probably, if attention were directed to it, the 

 play of regelation might be observed in the icebergs of the ocean. 



