Sir Hans, eminently distinguished as a physician and a naturalist, was of Irish birth but of Scottish extraction, his father, Alexander Sloane, having been at the head of that Scottish colony which King James I. settled in the north of Ireland, where the son was born, at Killyleagh, in the county of Down, on the 16th of April 1660. The place of his birth, a small two-storied house, is still pointed out in a back street of the town. At a very early period, he displayed a strong inclination for natural history; and this propensity being encouraged by a suitable education, he employed those hours which young people generally lose by pursuing low and trifling amusements, in the study of nature, and contemplating her works. When about sixteen, he was attacked by a spitting of blood, which threatened to be attended with considerable danger, and which interrupted the regular course of his application for three years. He had, however, already learned enough of physic to know that a malady of this kind was not to be suddenly removed, and he prudently abstained from wine and other liquors that were likely to increase it. By strictly observing this severe regimen, which he in some measure continued ever afterwards, he was enabled to prolong his life beyond the ordinary bounds; being an example of the truth of his own favourite maxim, that sobriety, temperance, and moderation, are the best and most powerful preservatives that nature has granted to mankind. As soon as he recovered from this infirmity, he resolved to perfect himself in the different branches of physic, which was the profession he had made choice of; and with this view he repaired to London, where he hoped to receive that assistance which he could not find in his own country.

On his arrival in the metropolis, he entered himself as a pupil of Stafford, an excellent chemist, bred under the illustrious Stahl; and by his instructions he gained a perfect knowledge of the composition and preparation of the different kinds of medicines then in use. At the same time, he studied botany at the garden at Chelsea, assiduously attended the public lectures of anatomy and physic, and in short neglected nothing that he thought likely to prove serviceable to him in his future practice. His principal merit, however, was his knowledge of natural history; and it was this part of his character which introduced him early to the acquaintance of Boyle and Ray, two of the most eminent naturalists of that age. His intimacy with these distinguished characters continued as long as they lived; and as he was careful to communicate to them every object of curiosity that attracted his attention, the observations which he occasionally made often excited their admiration and obtained their applause. After studying four years in London with unremitting severity, Sloane determined to visit foreign countries for further improvement. With this view he set out for France in the company of two other students, and having crossed to Dieppe, proceeded to Paris. In the way thither they were entertained by Lemery the elder; and in return Sloane presented that eminent chemist with a specimen of four different kinds of phosphorus, of which, upon the credit of other writers, Lemery had treated in his book of chemistry, though he had never seen any of them. At Paris Sloane lived as he had done in London. He attended the hospitals, heard the lectures of Tournefort, De Verney, and other eminent masters; visited all the literati, who received him with particular marks of esteem; and employed himself wholly in study. From Paris he proceeded to Montpellier; and, being furnished with letters of recommendation from Tournefort to Chirac, then chancellor of that university, he found easy access, through his means, to all the learned men of the province, particularly to Magnol, whom he always accompanied in his botanical excursions in the environs of that city. Having here found an ample field for contemplation, which was entirely suited to his taste, he took leave of his two companions, whom a curiosity of a different kind led into Italy. After spending a whole year in collecting plants, he travelled through Languedoc with the same design; and passing through Toulouse and Bordeaux, returned to Paris, where he made a short stay. About the end of the year 1684 he set out for England, with an intention of settling there as a physician. On his arrival in London, he made it his first business to visit his two illustrious friends Ray and Boyle, in order to communicate to them the discoveries which he had made in his travels. The latter he found at home, but the former had retired to Essex; to which place Sloane transmitted a great variety of plants and seeds, which Ray has described in his History of Plants, and for which he makes a proper acknowledgment.

About this time Sloane became acquainted with Sydenham, who soon contracted so warm an affection for him that he took him into his house, and recommended him in the strongest manner to his patients. He had not been long in London before he was proposed by Dr Martin Lister as a candidate to be admitted a Fellow of the Royal Society, on the 26th of November 1684; and being approved, he was elected on the 21st of January following. In 1685 he communicated some curiosities to the Society; and in July the same year he was a candidate for the office of secretary, but without success, as he was obliged to give way to the superior interest of his competitor Dr Halley. On the 12th of April 1687, he was chosen a fellow of the College of Physicians in London; and on the 13th of July of the same year his friend and fellow-traveller Dr Tancred Robinson, having mentioned to the society the plant called "the star of the earth" as a remedy newly discovered for the bite of a mad dog, Dr Sloane acquainted them that this virtue of the plant was to be found in a book called De Grey's Farriery; and that he knew a man who had cured with it twenty couple of dogs. On the 12th of September following he embarked at Portsmouth for Jamaica with the Duke of Albemarle, who had been appointed governor of that island. The doctor attended his grace in quality of physician, and arrived at Jamaica on the 19th of December following. Here a new field was opened for fresh discoveries in natural productions; but the world would have been deprived of the fruits of them had not Sloane, by incredible application, converted, as we may say, his minutes into hours. The Duke of Albemarle died soon after he landed, yet he so improved his time in making collections of natural curiosities, that, though his whole stay in Jamaica was not above fifteen months, he brought together such a prodigious number of plants, that, on his return to England, Ray was astonished that one man could procure in one island, and in so short a space, so vast a variety. On his arrival in London, he applied himself to the practice of his profession, and soon became so eminent, that he was chosen physician to Christ's Hospital on the 17th October 1694; and this office he held till the year 1730, when, on account of his great age and infirmities, he found it necessary to resign. It is somewhat singular, and redounds much to the doctor's honour, that though he received the emoluments of his office punctually, because he would not lay down a precedent which might hurt his successors, yet he constantly applied the money to the relief of those who were the greatest objects of compassion in the hospital, that it might never be said he enriched himself by giving health to the poor. He had been elected secretary to the Royal Society on the 30th of November 1692; and upon this occasion he revived the publication of the Philosophical Transactions, which had for some time been neglected. He continued to be the editor of this work till the year 1712; and the volumes which appeared during that period are monuments of his industry and ingenuity, many of the pieces contained in them being written by himself. In the meantime he published Catalogus Plantarum quae in Insula Jamaicae sponte proveniant; seu Prodromi Historiae Naturalis pars prima; which he dedicated to the Royal Society and the College of Physicians. About the same time he formed the plan of a dispensary, where the poor might be furnished at prime cost with such medicines as their several maladies might require; and this he afterwards carried into execution, with the assistance of the president and other members of the College of Physicians. His eager thirst for natural knowledge seems to have been born with him, so that his cabinet of curiosities may be said to have commenced with his life. He was continually enriching and enlarging it; and the fame which, in the course of a few years, it had acquired, brought everything that was curious in art or nature to be first offered to him for purchase. These acquisitions, however, increased it but very slowly in comparison of the augmentation which it received in 1701 by the death of William Courten, a gentleman who had employed all his time, and the greater part of his fortune, in collecting rarities, and who bequeathed the whole to Dr Sloane, on condition of his paying certain debts and legacies with which he had charged it. These terms our author accepted, and he executed the will of the donor with the most scrupulous exactness; on which account some people have said, that he purchased Courten's curiosities at a dear rate.

In 1707, the first volume of Dr Sloane's Natural History of Jamaica appeared in folio, though the publication of the second was delayed till 1725. By this very useful as well as magnificent work, the materia medica was enriched with a great number of excellent drugs not before known. In 1708, the author was elected a foreign member of the Royal Academy of Sciences at Paris, in the room of Tschirnhaus; an honour so much the greater as we were then at war with France, and the queen's express consent was necessary before he could accept it. In proportion as his credit rose among the learned, his practice increased among the people of rank. Queen Anne herself frequently consulted him. On the advancement of George I. to the throne, that prince, on the 3rd of April 1716, created Sloane a baronet, an hereditary title of honour to which no English physician had before attained; and at the same time made him physician-general to the army, in which station he continued till 1727, when he was appointed physician in ordinary to George II. He attended the royal family till his death; and was particularly favoured by Queen Caroline, who placed the greatest confidence in his prescriptions. In the meantime, he had been unanimously chosen one of the elects of the College of Physicians on the 1st of June 1716, and he was elected president of the same body on the 30th of September 1719, an office which he held for During that period he not only gave the highest proofs of his zeal and assiduity in the discharge of his duty, but, in 1721, made a present to that society of L100, and so far remitted a very considerable debt which the corporation owed him as to accept it in such small sums as were least inconvenient to the state of their affairs.

Sir Hans was no less liberal to other learned bodies. He had no sooner purchased the manor of Chelsea, than he gave the company of apothecaries the entire freehold of their botanical garden. He gave besides several other considerable donations for the improvement of this garden, the situation of which, on the banks of the Thames, and in the neighbourhood of the capital, was such as to render it useful in two respects: first, by producing the most rare medicinal plants; and, secondly, by serving as an excellent school for young botanists, an advantage which he himself had derived from it in the early part of his life.

The death of Sir Isaac Newton, which happened in 1727, made way for the advancement of Sir Hans to the presidency of the Royal Society. He had been vice-president, and frequently sat in the chair for that great man; and by his long connection with this learned body he had contracted so strong an affection for it, that he made the Society a present of an hundred guineas, caused a curious bust of Charles II., its founder, to be erected in the great hall where it met, and, as is said, was very instrumental in procuring Sir Godfrey Copley's benefaction of a medal of the value of five guineas, to be annually given as an honorary mark of distinction to the person who should communicate the best experiments to the Society. On his being raised to the chair, Sir Hans applied himself wholly to the faithful discharge of the duties of the offices which he enjoyed. In these laudable occupations he employed his time, from 1727 to 1740, when, at the age of fourscore, he formed a resolution of retiring into private life. With this view, he resigned the presidency of the Royal Society much against the inclination of that respectable body, who chose Martin Folkes to succeed him, and in a public assembly thanked him for the great and eminent services which he had rendered them.

In the month of January 1741, he began to remove his library, and his cabinet of rarities, from his house in Bloomsbury to that at Chelsea; and, on the 12th of March following, having settled all his affairs, he retired thither himself, to enjoy in peaceful tranquillity the remains of a well-spent life. He did not, however, bury himself in that solitude which excludes men from society. He received in Chelsea, as he had done in London, the visits of people of distinction, of learned foreigners, and of the royal family, who sometimes did him the honour to wait on him; but, what was still more to his praise, he never refused admittance or advice to rich or poor who came to consult him concerning their health. Not contented with this contracted method of doing good, he now, during his retreat, presented to the public such useful remedies as success had warranted, during the course of a long-continued practice. During the whole course of his life Sir Hans had lived with so much temperance as had preserved him from feeling the infirmities of old age; but in his ninetieth year he began to complain of pains, and to be sensible of a universal decay. He was often heard to say, that the approach of death brought no terrors along with it; that he had long expected the stroke; and that he was prepared to receive it whenever the Great Author of his being should think fit. After a short illness of three days, he died on the 11th of January 1752, in his ninety-second year, and was interred on the 18th at Chelsea, in the same vault with his lady, his remains being attended by the greatest concourse of people, of all ranks and conditions, that had ever before been seen on a like occasion.

Sir Hans being extremely solicitous lest his cabinet of curiosities, which he had taken so much pains to collect, should be again scattered at his death, and being at the same time unwilling that so large a portion of his fortune should be lost to his children, bequeathed it to the public, on condition that L20,000 should be made good by parliament to his family. The sum, though large in appearance, was scarcely more than the intrinsic value of the gold and silver medals, the ores and precious stones that were found in it; for in his last will he declares, that the first cost of the whole amounted at least to L50,000. Besides his library, consisting of more than fifty thousand volumes, three hundred and forty-seven of which were illustrated with cuts finely engraven and coloured from nature, there were three thousand five hundred and sixty manuscripts, and an infinite number of rare and curious works of every kind. The parliament accepted the legacy, and fulfilled the conditions, and from this ample collection the British Museum had its origin.