THE theory of constructive impact, of which a popular account is given in the present book, appears to have had its origin in an attempt to explain the phenomena of new stars by the grazing collision of two dark bodies. Hitherto the theory has not been hospitably received by astronomers, and the more elaborate exposition now presented will probably meet no better fate. The truth seems to be that in spite of his claim to have discovered numerous facts not known to “ordinary” astronomers, the author lacks familiarity with spectroscopic work and astronomical methods generally. He quite condemns himself by suggesting (p. 235) that more confirmatory evidence in the case of Nova Aurigæ was only wanting because astronomers, unguided by the theory, did not make “more liberal and careful observation.” As a matter of fact, the most valuable records were photographic, and are still as much in evidence as during the visibility of the Nova, and the observations certainly cannot be interpreted as indicating the presence of three bodies of the kind required by the theory. The theory thus breaks down at the outset, and it would not be difficult to show the weakness of most of the “overwhelming” astronomical evidence on which depends its extension into collisions of nebulæ, clusters and cosmic systems by which it is argued that the existing forms and distribution of celestial bodies are completely explained. The merest possibilities are frequently magnified into certainties, as, for example, the occurrence of variable stars in pairs, and the preponderance of variability in double stars.