108 Mr. T. Andrews. [June 5, 



the experiments at 32 F. On repeating the experiments in every 

 instance, the water for the ice block was first frozen by the applica- 

 tion of a temperature of F., which was afterwards reduced to 

 35 F. In making the observations, the extent of the penetration 

 of the steel rod at the latter low temperature was first taken ; the ice 

 was then allowed gradually to acquire throughout a temperature of 

 F., and its penetrability ascertained ; the ice block was afterwards 

 allowed to reach the temperature of 28 and 32 F., and the final 

 measurements obtained. The results recorded are the average of 

 numerous measurements taken directly at different places on the ice 

 block a sufficient distance apart, the indentation caused by the 

 previous penetration of the rod being filled with water, which rapidly 

 froze up. The variation in penetrability at different places on the 

 ice block when measurements were taken at the same temperature 

 was not great. 



The polished steel rod used for ascertaining the penetrability was 

 16 inches long and 0'292 inch diameter; its extremity was a flat disk, 

 so as to avoid any liability of shearing action. The rod was main- 

 tained in an upright position by a suitable arrangement of guides, 

 and error arising from its conductivity was obviated by surrounding 

 it throughout its length with fine sawdust contained in a loosely 

 fitting bag which surrounded it. The weight, of 181| Ib. (inclusive 

 of the weight of the platform, and guides), was placed on a sliding 

 wood platform working in a frame, the whole weight resting during 

 experimentation on the top of the steel rod (see fig. 1). 



Repeated observations were made in the above manner with the 

 results recorded on Diagram I. 



I also made a large number of experiments on the plasticity of 

 natural lake or pond ice, which were conducted in a somewhat similai 

 manner ; the results showed a greater absence of uniformity in the* 

 amount of penetration when compared with results at a similar tem- 

 perature obtained from the specially prepared pure ice blocks. The 

 observations were taken on the surface of the ice of a large artificial 

 lake or dam, being a storage reservoir for Wortley Iron Works, about 

 4 acres in extent, the depth varying from about 8 to 10 feet, the thick- 

 ness of the ice being given on Diagram II. The water of this pond 

 is still, no current of water passing through it ; it is therefore practi- 

 cally a small lake. The observations were taken after sunset, and 

 mostly throughout the long cold nights, so as to avoid, as far as 

 possible, any influence of the sun on the surface of the pond ice. A 

 number of measurements were taken adjacently in one locality of the 

 pond, the apparatus being removed to another part for another set of 

 observations, and so on, till the completion of the results. The obser- 

 vations were taken at various periods extending over some time. 

 Thermometers were inserted in the ice, and the atmospheric tern- 



