In recent years a number of scholars have argued that Faraday's theories of matter and force were founded on concepts which were derived from Boscovich's Theoria Philosophiae Naturalis (1758). The notion that Faraday's ideas display Boscovichean tendencies is not a new one: it was proposed by several of Faraday's immediate successors and has been noted by more recent commentators. Statements of this kind are not implausible as assertions of a general correspondence between Faraday's views on matter, as expressed in the “Speculation touching Electric Conduction and the Nature of Matter” of 1844, and Boscovich's theory of point atomism, but Professor L. Pearce Williams has made much stronger claims for the dependence of Faraday's ideas on Boscovich's theory of matter. Williams' interpretation has been questioned by recent scholarship, and in this paper I wish to advance an alternative interpretation of Faraday's ideas on electricity and the nature of matter.

The modern corpuscular theory of radiation was born in 1905 when Einstein advanced his light quantum hypothesis; and the steps by which Einstein's hypothesis, after years of profound scepticism, was finally and fully vindicated by Arthur Compton's 1922 scattering experiments constitutes one of the most stimulating chapters in the history of recent physics. To begin to appreciate the complexity of this chapter, however, it is only necessary to emphasize an elementary but very significant point, namely, that while Einstein based his arguments for quanta largely on the behaviour of high-frequency black body radiation or ultra-violet light, Compton experimented with X-rays. A modern physicist accustomed to picturing ultra-violet light and X-radiation as simply two adjacent regions in the electromagnetic spectrum might regard this distinction as hair-splitting. But who in 1905 was sure that X-rays and γ-rays are far more closely related to ultra-violet light than to α-particles, for example ? This only became evident after years of painstaking research, so that moving without elaboration from Einstein's hypothesis to Compton's experiments automatically eliminates from consideration an important segment of history—a segment in which a major role was played by William Henry Bragg.