In writing the History of discoveries relating to vision, I was much assisted by Mr. Michell, the discoverer of the method of making artificial magnets. Living at Thornhill, not very far from Leeds, I frequently visited him, and was very happy in his society, as I also was in that of Mr. Smeaton, who lived still nearer to me. He made me a present of his excellent air pump, which I constantly use to this day. Having strongly recommended his construction of this instrument, it is now generally used; whereas before that hardly any had been made during the twenty years which had elapsed after the account that he had given of it in the Philosophical Transactions. I was also instrumental in reviving the use of large electrical machines, and batteries, in electricity, the generality of electrical machines being little more than play things at the time that I began my experiments. The first very large electrical machine was made by Mr. Nairne in consequence of a request made to me by the Grand Duke of Tuscany, to get him the best machine that we could make in England. This, and another that he made for Mr. Vaughan, were constituted on a plan of my own. But afterwards Mr. Nairne made large machines on a more simple and improved construction; and in consideration of the service which I had rendered him, he made me a present of a pretty large machine of the same kind. The review of my history of electricity by Mr. Bewley, who was acquainted with Mr. Michell, was the means of opening a correspondence between us, which was the source of much satisfaction to me as long as he lived. I instantly communicated to him an account of every new experiment that I made, and, in return, was favoured with his remarks upon them. All that he published of his own were articles in the _Appendixes_ to my volumes on air, all of which are ingenious and valuable. Always publishing in this manner, he used to call himself my _satellite_. There was a vein of pleasant wit and humour in all his correspondence, which added greatly to the value of it. His letters to me would have made several volumes, and mine to him still more. When he found himself dangerously ill, he made a point of paying me a visit before he died; and he made a journey from Norfolk to Birmingham, accompanied by Mrs. Bewley, for that purpose; and after spending about a week with me, he went to his friend Dr. Burney, and at his house he died.