PROF. H. A. HARRIS, of the Anatomy School, Cambridge, has directed our attention to a statement by Richard Watson (1737-1816), bishop of Llandaff and professor of chemistry at Cambridge, an account of whose work was recently given by Prof. J. R. Partington (Chemistry and Industry, 56, 819 ; 1937). Prof. Harris quotes from Watson's "Chemical Essays" (vol. 4, Essay 7), "Of the Transmutability of Water into Earth", in which he says "the diversities of bodies subsisting in the universe, will no longer be attributed to the different combinations of earth, air, fire and water, as distinct, undecompounded, immutable principles ; but to the different magnitudes, figures, and arrangements of particles of matter of the same kind". This idea of a composition of particles of what were then believed to be elements from simpler particles in different arrangements and motions is to be found also in the "Sceptical Chymist" of Robert Boyle, written in 1661, in which he says: "The greatest part of the affections of matter, and consequently of the Phaenomena of nature, seems to depend upon the motion and the contrivance of the small parts of Bodies", and that "the difference of Bodies may depend meerly upon that of the schemes whereinto their common matter is put ... so that according as the small parts of matter recede from each other, or work upon each other ... a Body of this or that denomination is produced". In these statements of Boyle and Watson an idea of the present view of the structure of the elements is expressed.