1. Playfair , John . 1802.Illustrations of the Huttonian Theory of the Earthiii–iii. Edinburgh I quote from the facsimile reprint, intro. George W. White (Urbana, 1956). In his biographical account of Hutton (1803; pub. 1805), Playfair comments twice on Hutton's style, both times negatively (pp. 61–62; 83).
2. This quotation, noticed by Rappaport, appears in Freshfield Douglas W.The Life of Horace Benedict de SaussureLondon 1920 466a 466a (with Henry F. Montagnier) The letter is in private hands.
3. First noted by Schofield Robert E.The Lunar Society of BirminghamOxford 1963 280 280 note 2, but inaccurately. I am grateful to W. A. Taylor, City Librarian, Birmingham Public Libraries, for a photocopy of the original letter, which is in their Boulton and Watt collection.