I. A SURVEY of the progress made during the last twenty five years in almost any field of engineering work would show an immense advance. Even during the past ten years very considerable progress has ...

UNDER this heading, two books on internal combustion engines, one by Prof. W. E. Dalby and the other by Mr. H. R. Ricardo, were recently reviewed in these columns (NATURE, NOV. 28, 1931, p. 886). Mr.