 There is some evidence that Shepherd anonymously published a book critical of Brown in 1819, the year after his treatise on causality appeared. This is suggested by a note attached to a volume in the Cambridge University Library which is included in the facsimile reproduction of Shepherd’s philosophical works edited by Jennifer McRobert. This book has two parts: one compares the causal theories of Brown and Hume with observations “calculated to shew the inconsistency of these theories”; its treatment of causality is said to be inspired by recent developments in chemical science. The other, titled “New Theory of the Earth”, proposes to explain the origin of prominent features of the earth on the basis of motions due to gravitational force, various conflagrations and collisions. There may be a connection between the view of causality urged in this volume and the books published under her name. But the factual objections to Hume are tame in comparison with the logical critique and ambitious metaphysical and epistemic system in the later volumes. Although Shepherd’s authorship of the earlier book is probable, it is not entirely certain. 