1. Wedgwood J. , A Memorial relative to a Petition from Mr. Champion for the Extension of a Patent, quoted by Owen H. , Two Centuries of Ceramic Art in Bristol (1873), p. 121
2. Smiles Samuel , Boulton and Watt (1878), p. 157
3. Lord J. , Capital and Steam Power (1923), p. 102
4. Bargar , op. cit. p. 29