ON AN EXPERIMENTAL INVESTIGATION INTO THE FLOW OF MARBLE. 377 
rock rather by the ends that across the badly-conducting air space (E). The whole 
is well lagged with asbestos. The heat is supplied by means of a Bunsen flame. The 
temperature, which was observed thrice daily, was maintained as nearly as possible at 
300° C., and was within a few degrees of this most of the time, the extreme limits of 
Fig. 1. 
variation being 270° C. and 352° C. The marble was maintained at this temperature 
for 124 days, or four months, and was during this time deformed as slowly as possible 
and at as nearly as jiossible a constant rate. The dimensions of the column in inches 
are given in the following table :— 
3 C 
VOL. CXGV.—A. 
