Dr Frank, physician and anatomist, was born in London in the year 1699. His father was a barrister at law; and both his parents were of good families in Cornwall. After receiving the first rudiments of his education at a private school in the country, where his docility and sweetness of temper endeared him equally to his master and his school fellows, Frank was in a few years removed to Westminster, and from thence to Oxford, where he was admitted a commoner (or sojourner) of Exeter college, under the tuition of Mr John Haviland, on March 4, 1714. There he applied himself diligently to all the usual academical studies, but particularly to natural philosophy and polite literature. Nicholls, literature, of which the fruits were most conspicuous in his subsequent lectures on physiology. After reading a few books on anatomy, in order to perfect himself in the nomenclature of the animal parts then adopted, he engaged in dissections, and then devoted himself to the study of nature, perfectly free and unbiased by the opinions of others.

On his being chosen reader of anatomy in that university, he employed his utmost attention to elevate and illustrate a science which had there been long depressed and neglected; and by quitting the beaten track of former lecturers, and minutely investigating the texture of every bowel, the nature and order of every vessel, &c. he gained a high and just reputation. He did not then reside at Oxford; but when he had finished his lectures, used to repair to London, the place of his abode, where he had determined to settle. He had once an intention of fixing in Cornwall, and for a short time practised there with great reputation; but being soon tired of the fatigues attendant on that profession in the country, he returned to London, bringing back with him a great insight, acquired by diligent observation, into the nature of the military fever, which was attended with the most salutary effects in his subsequent practice at London.

About this time he resolved to visit the continent, partly with a view of acquiring the knowledge of men, manners, and languages; but chiefly to acquaint himself with the opinions of foreign naturalists on his favorite study. At Paris, by conversing freely with the learned, he soon recommended himself to their notice and esteem. Winslow's was the only good system of physiology at that time known in France, and Morgagni's and Santorini's of Venice in Italy, which Dr. Nicholls likewise soon after visited. On his return to England, he repeated his physiological lectures in London, which were much frequented, not only by students from both the universities, but also by many surgeons, apothecaries, and others. Soon after, his new and successful treatment of the military fever, then very prevalent in the southern parts of England, added much to his reputation. In 1725, at a meeting of the Royal Society, he gave his opinion on the nature of aneurisms, in which he dissented from Dr. Freind in his History of Physic.

At the beginning of the year 1728, he was chosen a fellow of the Royal Society, to which he afterwards communicated the description of an uncommon disorder (published in the Transactions), viz., a polypus, resembling a branch of the pulmonary vein (for which Tulpus has strangely mistaken it), coughed up by an asthmatic person. He also made observations (in the same volume of the Transactions) on a treatise, by M. Helvetius of Paris, on the lungs. Towards the end of the year 1729, he took the degree of doctor of physic at Oxford. At his return to London, he underwent an examination by the president and censors of the College of Physicians, previous to his being admitted a candidate, which every practitioner must be a year before he can apply to be chosen a fellow. Dr. Nicholls was chosen into the college on June 26, 1732; and two years after, being chosen Gulstonian reader of Pathology, he made the structure of the heart, and the circulation of the blood, the subject of his lectures. In 1736, at the request of the president, he again read the Gulstonian lecture; taking for his subject those parts of the human body which serve for the secretion and discharge of the urine; and the causes, symptoms, and cure of the diseases occasioned by the stone. In 1739, he delivered the anniversary Harveian oration. In 1743, he married Elizabeth, youngest daughter of the celebrated Dr. Mead, by whom he had five children, two of whom died young. Two sons and a daughter survived him.

In 1748, Dr. Nicholls undertook the office of chirurgical lecturer, beginning with a learned and elegant dissertation on the Anima Medica. About this time, on the death of Dr. John Cunningham, one of the elects of the college, Dr. Abraham Hall was chosen to succeed him in preference to our author, who was his senior, without any apparent reason. With a just resentment, he immediately resigned the office of chirurgical lecturer, and never after attended the meetings of the fellows, except when business of the utmost importance was in agitation.

In 1751, he took some revenge in an anonymous pamphlet, entitled "The petition of the Unborn Babes to the Censors of the Royal College of Physicians of London;" in which Dr. Nesbit (Poens), Dr. Maule (Maudus), Dr. Barrowby (Barbome), principally, and Sir William Brown, Sir Edward Hulse, and the Scots incidentally, are the objects of his satire.

In 1753, on the death of Sir Hans Sloane, Bart. in his 94th year, Dr. Nicholls was appointed to succeed him as one of the king's physicians, and held that office till the death of his royal master in 1760; when this most skilful physician was superseded with something like the offer of a pension, which he rejected with disdain.

The causes, &c. of the uncommon disorder of which the late king died, viz. a rupture of the right ventricle of the heart, our author explained in a letter to the earl of Macclesfield, president of the Royal Society, which was published in the Philosophical Transactions, vol. I.

In 1772, to a second edition of his treatise De Anima Medica, he added a dissertation De motu cordis et sanguinis in homine nato et non nato, inscribed to his learned friend and coadjutor the late Dr. Lawrence.

Tired at length of London, and also desirous of superintending the education of his son, he removed to Oxford, where he had spent most agreeably some years in his youth. But when the study of the law recalled Mr. Nicholls to London, he took a house at Epsom, where he passed the remainder of his life in a literary retirement, not inattentive to natural philosophy, especially the cultivation of grain, and the improvement of barren soils, and contemplating also with admiration the internal nature of plants, as taught by Linnæus.

His constitution never was robust. In his youth, at Oxford, he was with difficulty recovered from a dangerous fever by the skill of Doctors Frampton and Frewen; and afterwards at London he had frequently been afflicted with a catarrh, and an inverterate asthmatic cough, which, returning with great violence at the beginning of the year 1778, deprived the world of this valuable man on January 7th, in the 80th year of his age.

Dr. Lawrence, formerly president of the college of physicians, who gratefully ascribed all his physiological and medical knowledge to his precepts, and who, while he Nicholls, he lived, loved him as a brother, and revered him as a parent, two years after printed, and gave to his friends, a few copies of an elegant Latin Life of Dr. Nicholls (with his head prefixed, a striking likeness, engraved by Hall from a model of Gosset, 1779; from which, through the medium of the Gentleman's Magazine, the above particulars are chiefly extracted.