With a view to showing that distortion under stress may take place in ice when several degrees below the freezing-point, Dr. Main made a number of experiments at St. Moritz in the Engadine during the winter of 1887. Although, as Main says, “The experiments are to be regarded rather as proving the existence of continuous extension under tensile stress than as determining its amount,” the records of his tests are sufficiently detailed to admit of the viscosity being calculated.