122 ICE-GAUGE PLACED. [February, 



February 24. In November last I alluded to experi- 

 ments then commenced, in order to determine the very 

 contradictory assertions made as to the ratio in which 

 salt-water ice, or the floe, freezes. In order to test this 

 question satisfactorily, I caused a wooden tube to be 

 formed, having its two opposite sides partially open ; in 

 fact, the two complete and parallel sides were simply re- 

 tained in their position by battens. 



This tube was inserted in a hole cut on the smoothest 

 part of the floe, the surrounding ice being of very even 

 thickness, viz. eighteen inches. A cross batten on the 

 upper surface was placed, not only for the purpose of 

 upper level gauge and suspension, but also to determine 

 if any increment took place on the upper surface by 

 evaporation from beneath, or from consolidation of the 

 superior snow by a similar action of escaping vapour; 

 or, in plain terms, two questions were to be solved : 



1. Does the ice increase solely from the water be- 

 neath ? Or, 



2. Does it owe any part of its increase either to va- 

 pour escaping (on freezing) by percolation through the 

 crust, and consolidation above? 



On radii, from the gauge as a centre, holes were cut 

 every ten clays, and the thickness of the ice strictly 

 gauged. The result on withdrawing the gauge at the 

 end of 110 days affords the following table, which, as 

 the batten still occupied its original position, also proved 

 that the increment has been solely from beneath. 



The tube was inserted November 5 ; the upper level, 

 five feet six inches ; ice thickness, eighteen inches ; space 

 above gauge, eighteen inches. 



