The idea of the atom as the building block of matter has developed over time. What was thought of as a single particle about 1 × 10‾¹⁰ m across is now known to be a collection of smaller particles.

I CONCUR with Prof. Rutherford (NATURE, December 11, p. 423) that the work by Moseley in the current number of the Philosophical Magazine, which was not published, and was quite unknown to me when I ...