206 A. Bigelow on the Freezing of Water. 
while moisture oozed out on the surface; but, on the instant of — 
its removal the plates regained their appearance and position; 
showing that there were intervening spaces filled with water. 
The extent of surface was about two square feet. 
Directing the water to be drawn off, I left it till the next 
i d 
remaining. The next day was warmer, the ice began to melt, 
and the plates were again apparent, less perfect than before but 
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bly at an acute angle, forming rhombs whose angles were slightly 
rounded. Fig. 2. 
I looked daily for these appearances, as I passed back and 
forth, for nearly a mile, between the canal and the river, and 
frequently during the mild weather of the succeeding winter 
months observed the facts mentioned in the first case, with this 
difference, that when the cavities were apparent in thin ice formed 
as usual on the surface of the water, the sides diverged down- 
ward, being the reverse, in position, of those mentioned in case 
first. When water freezes rapidly, the originating centres @ an 
be many, the series of plates of small extent, the cavities filled 
up, a homogeneous mass formed, and no sign of its structure 
apparent until the slow thawing of spring reveals it, as we shall 
show. 
