(κρύος, frost, φόρος, to bear), a name given by Dr Wollaston to an instrument of his invention, which serves to illustrate the theory of heat. The form of this instrument may be readily conceived without a figure. It is a glass tube, bent at each end, the bent parts terminating in hollow glass balls, D and E. The ball D is half filled with water. A vacuum is produced in the tube and ball E, by boiling the water in the ball D, whilst the capillary aperture in the ball E, through which the steam is issuing, is held in the flame of a lamp till the steam becomes