SWAN (John). Explanation of an Improved Mode of Tanning; laid down from Practical Results; Intended to Accompany the New Invented Barktrometer, which will be found an unerring guide to the True Art of Tanning.1821

London: Printed for the Author, and to be had only of him, First edition, 8vo (185 x 115 mm), iv, [2], [5]-143, [1]pp., copperplate frontispiece showing 'apparatus for ascertaining the real value of Bark', a little foxed and offset onto title, cont. calf, rubbed, neatly rebacked, morocco label to spine. John Swan, described on the title page as Mathematical Instrument Maker, of Granby-street, Leicester, and 20, Little Tower, London. The Barktrometer was used by tanners for ascertaining the density of tanning fluid. Ron, Bibliotheca Tinctoria, 1015.