First and only edition, 4to, 10pp.,one fold-out engraved plate with six illustrations, recent quarter calf, marbled paper boards, red morocco title label on upper cover. Canton's invention of a technique for magnetizing iron bars to produce artificial magnets. A way of doing this had been discovered shortly before by Gowin Knight, who kept the method secret while he sought to exploit its commercial possibilities; these were considerable on account of the consequential improvements to the mariner's compass. Knight's success encouraged others to take up the subject. Canton seems to have begun experimenting in 1747 out of frustration at the price Knight wanted to charge him for a pair of magnets. His first successes led him to toy briefly with the idea of going into business himself. He showed his method to visitors including David Fordyce, professor at Aberdeen, who may have been responsible for Canton's being awarded an MA degree by King's College, Aberdeen, in April 1750. John Michell in Cambridge had also been experimenting on producing magnets and in 1750 published his method. This prompted Canton to report his own, very similar, technique to the Royal Society, of which he had that year become a fellow. Michell accused him of plagiarism but no one in London believed the charge since they knew that Canton had been producing magnets for several years. So unconvinced of the allegation were members of the Royal Society, indeed, that the society awarded him its Copley medal for 1751 for his work. Dictionary of Scientific Biography III, p. 51.
