1888.] On the Plasticity of Glacier and other Ice. 345 



Fig. 3. 



allowance is made for the resulting error. Two lever systems were 

 required, one for the outer ends, and the other for the inner ends of 

 the needles passing through the ice. In Experiment 2 we used two 

 scales and mirrors which enabled the readings to be taken with great 

 accuracy. Afterwards we contented ourselves with one, which gave 

 quite sufficient accuracy for any but homogeneous ice. In the first 

 few experiments we used glass fibres, both for the indicator and 

 connecting fibre, as we feared some slight motion of / might arise 

 from the " elastic recovery " of the wire. This was put to the test of 

 experiment. A long piece of the same kind of wire was bent sharply 

 at an angle, and the two ends brought nearly into contact. It was 

 hung over a nail, and the distance between the ends measured from 

 time to time. The effect of the gradual unbending of the angle would 



