(John), an ingenious natural philosopher, was born at Stroud, in Gloucestershire, in 1718; and was placed, when young, under the care of a Mr Davis, of the same place, a very able mathematician, with whom, before he had attained the age of nine years, he had gone through both vulgar and decimal arithmetic. He then proceeded to the mathematics, and particularly to algebra and astronomy, wherein he had made a considerable progress, when his father took him from school, and put him to learn his own business, which was that of a broad cloth weaver. This circumstance was not able to damp his zeal for the acquisition of knowledge. All his leisure time was devoted to the assiduous cultivation of astronomical science; and, by the help of the Caroline tables, annexed to "Wing's Astronomy," he computed eclipses of the moon and other phenomena. His acquaintance with that science he applied likewise to the constructing of several kinds of dials. But the studies of our young philosopher being frequently pursued to very late hours, his father, fearing that they would injure his health, forbade him the use of a candle in his chamber any longer than for the purpose of going to bed, and would himself often see that his injunction was obeyed. The son's thirst for knowledge was, however, so great, that it made him attempt to evade the prohibition, and to find means of secreting his light till the family had retired to rest, when he rose to prosecute undisturbed his favourite pursuits. It was during this prohibition, and at these hours, hours, that he computed, and cut upon stone, with no better an instrument than a common knife, the lines of a large upright sun-dial, on which, besides the hour of the day, was shown the rising of the sun, his place in the ecliptic, and some other particulars. When this was finished, and made known to his father, he permitted it to be placed against the front of his house, where it excited the admiration of several gentlemen in the neighbourhood, and introduced young Mr Canton to their acquaintance, which was followed by the offer of the use of their libraries. In the library of one of these gentlemen, he found "Martin's Philosophical Grammar," which was the first book that gave him a taste for natural philosophy. In the possession of another gentleman, a few miles from Stroud, he first saw a pair of globes; an object that afforded him uncommon pleasure, from the great ease with which he could solve those problems he had hitherto been accustomed to compute. The dial was beautified a few years ago at the expense of the gentlemen at Stroud, several of whom had been his school-fellows, and who continued still to regard it as a very distinguished performance.

Among other persons with whom he became acquainted in early life, was the late reverend and ingenious Dr Henry Miles of Tooting, a learned and respectable member of the Royal Society, and of approved eminence in natural knowledge. This gentleman, perceiving that Mr Canton possessed abilities too promising to be confined within the narrow limits of a country town, prevailed on his father to permit him to come to London. Accordingly he arrived at the metropolis March 4, 1737, and resided with Dr Miles at Tooting till the 6th of May following; when he articled himself, for the term of five years, as a clerk to Mr Samuel Watkins, master of the academy in Spital-square. In this situation, his ingenuity, diligence, and good conduct, were so well displayed, that on the expiration of his clerkship in May 1742, he was taken into partnership with Mr Watkins for three years; which gentleman he afterwards succeeded in Spital-square, and there continued during his whole life. In 1744, he married Penelope, the eldest daughter of Mr Thomas Colbrooke, and niece to James Colbrooke, Esq.; banker in London.

Towards the end of 1745, electricity, which seems early to have engaged Mr Canton's notice, received a very capital improvement by the discovery of the famous Leyden Phial. This event turned the thoughts of most of the philosophers of Europe to that branch of natural philosophy; and our author, who was one of the first to repeat and to pursue the experiment, found his assiduity and attention rewarded by many capital discoveries. Towards the end of 1749, he was concerned with his friend, the late Mr Benjamin Robins, in making experiments in order to determine to what height rockets may be made to ascend, and at what distance their light may be seen. In 1750 was read at the Royal Society, Mr Canton's "Method of making artificial magnets, without the use of, and yet far superior to, any natural ones." This paper procured him the honour of being elected a member of the Society, and the present of their gold medal. The same year he was complimented with the degree of M.A. by the university of Aberdeen; and, in 1751, was chosen one of the council of the Royal Society.

In 1752, our philosopher was so fortunate as to be the first person in England, who, by attracting the electric fire from the clouds during a thunder-storm, verified Dr Franklin's hypothesis of the similarity of lightning and electricity. Next year, his paper intitled, "Electrical Experiments, with an attempt to account for their several Phenomena," was read at the Royal Society. In the same paper Mr Canton mentioned his having discovered, by a great number of experiments, that some clouds were in a positive, and some in a negative, state of electricity. Dr Franklin, much about the same time, made the like discovery in America. This circumstance, together with our author's constant defence of the doctor's hypothesis, induced that excellent philosopher, immediately on his arrival in England, to pay Mr Canton a visit, and give rise to a friendship which ever after continued without interruption or diminution. In the "Lady's Diary for 1756," our author answered the prize question that had been proposed in the preceding year. The question was, "How can we call the shooting of stars be best accounted for; what is the substance of this phenomenon; and in what state of the atmosphere doth it most frequently show itself?" The solution, though anonymous, was so satisfactory to his friend, Mr Thomas Simpson, who then conducted that work, that he sent Mr Canton the prize, accompanied with a note, in which he said, he was sure that he was not mistaken in the author of it, as no one beholds, that he knew of, could have answered the question. Our philosopher's next communication to the public, was a letter in the "Gentleman's Magazine for September 1759," on the electrical properties of the tourmalin, in which the laws of that wonderful stone are laid down in a very concise and elegant manner. On December 13th, in the same year, was read at the Royal Society, "An attempt to account for the regular diurnal variation of the Horizontal Magnetic Needle; and also for its irregular variation at the time of an Aurora Borealis." A complete year's observations of the diurnal variations of the needle are annexed to the paper. On Nov. 5, 1761, our author communicated to the Royal Society an account of the Transit of Venus, June 6, 1761, observed in Spital-square. Mr Canton's next communication to the Society, was a letter addressed to Dr Benjamin Franklin, and read Feb. 4, 1762, containing some remarks on Mr Delaval's electrical experiments. On Dec. 16, in the same year, another curious addition was made by him to philosophical knowledge, in a paper, intituled, "Experiments to prove that water is not incomprehensible." These experiments are a complete refutation of the famous Florentine experiment, which so many philosophers have mentioned as a proof of the incomprehensibility of water. On St Andrew's day 1763, our author was the third time elected one of the council of the Royal Society; and on Nov. 8, in the following year, were read, before that learned body, his farther "Experiments and observations on the comprehensibility of water, and some other fluids." The establishment of this fact, in opposition to the received opinion, formed on the hasty decision of the Florentine academy, was thought to be deserving of the Society's gold medal. It was accordingly moved for in the council of 1764; and after several invidious delays, which terminated much to the honour of Mr Canton, it was presented to him Nov. 30, 1765.

The next communication of our ingenious author to the Royal Society, which we shall take notice of in this place, was on Dec. 22, 1769, being "An easy method of making a Phosphorus that will imbibe and emit light like the Bolognian stone; with experiments and observations." When he first showed to Dr Franklin the instantaneous light acquired by some of this phosphorus from the near discharge of an electrified bottle, the doctor immediately exclaimed, "And God said, let there be light, and there was light." The dean and chapter of St Paul's having, in a letter to the president, dated March 6, 1769, requested the opinion of the Royal Society relative to the best and most effectual method of fixing electrical conductors to preserve that cathedral from damage by lightning, Mr Canton was one of the committee appointed to take the letter into consideration, and to report their opinion upon it. The gentlemen joined with him in this business were, Dr Watson, Dr Franklin, Mr Delaval, and Mr Wilson. Their report was made on the 8th of June following; and the mode recommended by them has been carried into execution. The last paper of our author's, which was read before the Royal Society, was on Dec. 21, 1769; and contained "Experiments to prove that the Luminousness of the Sea arises from the putrefaction of its animal substances." In the account now given of his communications to the public, we have chiefly confined ourselves to such as were the most important, and which threw new and distinguished light on various objects in the philosophical world. Besides these, he wrote a number of papers, both in earlier and in later life, which appeared in several different publications, and particularly in the Gentleman's Magazine.

The close and sedentary life of Mr Canton, arising from an unremitting attention to the duties of his profession, and to the prosecution of his philosophical enquiries and experiments, probably contributed to shorten his days. The disorder into which he fell, and which carried him off, was a dropy. His death happened on March 22, 1772, in the 54th year of his age.