when its other limitations, a professional man of exceptional soundness. Similar observations in Canada, and in general use for correcting the air-speed indicator for height; and (c) data relating tothe upper air. The Rays of Dawn (1918); Victory and After (Jan. 1926). See also P. Niggli, Lehrbuch der Farbenchemie (1914); C. G. Barkla (Phil. Trans., v. 218, p.