SAMUEL, a very learned prelate of the Church of England, the son of the Rev. John Horsley, for many years clerk in orders at St Martin's in the Fields, and afterwards rector of Thorley in Hertfordshire, was born at his father's residence in St Martin's Churchyard in October 1733. He received his early education from his father, and was entered at Trinity-hall, Cambridge, where he applied himself to the study of mathematics, and the writings of the ancient and modern divines and logicians. Why he took no degree in arts cannot now be ascertained. We find, however, that in 1758 he took that of bachelor of laws, and became his father's curate at Newington, which living he succeeded to the following year, and held until his elevation to the episcopal bench in 1793, as Bishop of Rochester.

In April 1767 he was elected a fellow of the Royal Society, of which he continued for many years an active member; and about the same time he published a pamphlet on the Power of God, "deduced from the computable instantaneous productions of it in the solar system." This he allows to be a "very singular and whimsical speculation." In 1768 he went to Christ-Church, Oxford, as private tutor to Henegoe Earl of Aylesbury, then Lord Guernsey. In 1770, his first mathematical publication, Apollonii Pergei Inclinationum libri duo, was elegantly printed at the Clarendon press. This work, though severely criticized at the time, and in reality not distinguished by any peculiar felicity of restoration, does not appear to have injured his rising reputation; for in November 1773 he was appointed secretary to the Royal Society, and in 1774 he had the degree of doctor of civil law conferred on him at Oxford, and was presented by the Earl of Aylesbury to the rectory of Aldbury, in Surrey, along with which he obtained a dispensation to hold that of Newington. The same year he published Remarks on the Observations made in the Voyage towards the North Pole, for determining the acceleration of the Pendulum in Lat. 79. 51.

Dr Horsley having long meditated a complete edition of the works of Sir Isaac Newton, issued in 1776 proposals for printing it by subscription, in five volumes 4to; but the commencement of the undertaking was delayed by severe domestic affliction, nor was it completed until 1785. In the meanwhile his diligence and proficiency in science attracted the notice of Dr Lowth, who, on his promotion to the see of London in 1777, appointed Dr Horsley his domestic chaplain, collated him to a prebend in St Paul's Cathedral, and procured for him the situation, which had been held by his father, of clerk in orders at St Martin's in the Fields. In 1778, during the controversy between Dr Priestley, Dr Price, and others, on the subject of materialism and philosophical necessity, Dr Horsley published a sermon on Providence and Free Agency, in which he attempted to draw a distinction between the philosophical necessity of the moderns and the predestination of their ancestors. This discourse was evidently directed against the writings of Dr Priestley, but the latter did not take any immediate notice of the attack. In 1779 Dr Horsley resigned Aldbury, and in 1780 was presented to the living of Thorley, which he held by dispensation along with that of Newington. In 1783 he became deeply involved in a dispute with some members of the Royal Society, which ended in his withdrawing himself from that learned body.

Dr Horsley was now about to engage in that celebrated controversy with Dr Priestley, which was conducted on both sides in the fiercest spirit of polemical contention, but on that of Horsley with superior learning and ability. In 1782 Dr Priestley published a work in two volumes 8vo, entitled A History of the Corruptions of Christianity; at the head of which he placed both the Catholic doctrine of Christ's divinity, and the Arian doctrine of his pre-existence, in a nature far superior to the human, at the same time representing the Socinian doctrine of his mere humanity as the unanimous faith of the first Christians. Dr Horsley, conceiving that the best antidote to the poison contained in this work would be to destroy the credit of the writer and the authority of his name, made its imperfections, moral as well as literary, the subject of review in a charge delivered to the clergy of the archdeaconry of St Albans, at a deputation held on the 22d of May 1783. The specimens produced as evidence of the imperfections of the work and the incompetency of the author, may be reduced to six classes. First, instances of reasoning in a circle; second, instances of quotations misapplied through ignorance of the subject; third, instances of testimonies perverted through artful and forced constructions; fourth, instances of passages in the Greek fathers, misinterpreted through ignorance of the Greek language; fifth, instances of passages misinterpreted through ignorance of the Platonic philosophy; and, sixth, instances of ignorance of the phraseology of the earliest ecclesiastical writers. Dr Horsley concludes his charge by observing, "I feel no satisfaction in detecting the weakness of this learned writer's argument, but what arises from the consciousness that it is the discharge of some part of the duty which I owe to the Church of God." This vigorous and systematic attack staggered the admirers of Dr Priestley; but he himself felt none of the apprehension with which they were seized. His reply was entitled, Letters to Dr Horsley, in answer to his Animadversions on the History of the Corruptions of Christianity, with additional evidence that the primitive Christian Church was Unitarian, 1783, in 8vo. To this production, in which there are more errors of haste and infirmities of argument than could have been expected from one who had so much at stake, Dr Horsley replied in the same epistolary form, by Letters from the Archdeacon of St Alban's, in reply to Dr Priestley. Dr Priestley, in his Letters, had attempted to draw his adversary into a controversy respecting the divinity of Jesus Christ; but the latter, knowing that question to have been long since exhausted, defended his own argument, and confined himself to the collection of proofs from Dr Priestley's publications of his inability to throw any light upon the subject.

Dr Priestley, finding that his Letters had failed to produce the expected impression, now lost all temper; and in a second set of letters to the Archdeacon of St Alban's, which appeared in the autumn of 1784, threw aside all profession of personal regard, or even of ordinary civility. The charge of incompetency and ignorance was warmly retorted, and "the incorrigible dignitary" was charged with manifest misrepresentation of his adversary's argument; with injustice to the character of Origen, whose veracity he had called in question; and with the grossest perversion of ancient history. In a word, he was stigmatized as a "falsifier of history, and a defamer of the character of the dead." Regardless of this reproach, Dr Horsley remained silent for eighteen months. A sermon on the Incarnation, preached upon the feast of the Nativity in 1785, formed the prelude to the renewal of the contest on his part, and was, early in the ensuing spring, followed by Remarks on Dr Priestley's Second Letters to the Archdeacon of St Alban's, with Proofs of certain Facts asserted by the Archdeacon. This tract consists of two parts; one containing new specimens of Dr Priestley's temerity in assertion; and the other defending the attack upon Origen, and proving the existence of a Horsley, body of Christians at Ælia after the time of Hadrian, which was the fact upon which the Archdeacon's historical fidelity had been so loudly arraigned by Dr Priestley. With this publication Dr Horsley had intended that the controversy on his part should close; but having been induced to collect and republish what he had written (in one vol. 8vo, 1789), this led to a second perusal of Dr Priestley's Letters, which produced not only many important notes, but some disquisitions of considerable length; and as the Remarks on Dr Priestley's Second Letters had elicited a third set, in which he endeavoured to support the veracity of Origen, and to maintain his position respecting the orthodox Hebrews of the church at Ælia, these are replied to partly in the notes, and partly also in two of the disquisitions.

The reputation which Dr Horsley had now acquired, recommended him to the patronage of Lord Chancellor Thurlow, who presented him to a prebendal stall in the cathedral of Gloucester; and, by the interest of the same eminent person, he was, in 1788, promoted to the see of St David's. As a bishop, his conduct was exemplary and praiseworthy; in this character he fully answered the high expectations of eminent usefulness, which his elevation to the mitre had so generally raised. In his diocese, he carried through a general system of reform, regulated the condition of the clergy, introduced greater strictness with respect to candidates for admission into holy orders, preached frequently in the parish churches, and acted with Christian liberality towards the poor. Bishop Horsley's first charge to the clergy of St David's was delivered in 1790, and deservedly admired, as was also his animated speech in the House of Lords 31st May 1791, on the subject of the Catholic Bill. These effective displays are understood to have occasioned his subsequent promotion to the bishopric of Rochester and the deanery of Westminster, upon which he resigned the living of Newington.

During the agitating period between 1793 and the close of the century, Bishop Horsley ranged himself on the side of the government, and with great zeal and warmth opposed the enemies of the constitution, and the professors of democratic principles, under which categories were then included all those who sought for reform in the representation of the people as a guarantee for the removal of abuses, and the progressive improvement of our institutions, ecclesiastical as well as civil. As a senator, his talents and activity necessarily gave him weight; and there were few discussions of importance in which he did not take part. He was not, however, an every-day speaker, nor desirous of protracting the debate, unless he had something original or important to communicate. In 1802, he was translated to the bishopric of St Asaph, and resigned the deanery of Westminster. Until 1806, his vigour of body and mind remained unimpaired. In the month of July of that year he went to his diocese, and after a residence of two months intended to visit his patron Lord Thurlow at Brighton, where he arrived on the 20th of September, after learning on the road that his noble friend was no more. On the 30th, he became affected with a complaint in the bowels, which, slight at first, soon terminated in mortification, and on the 4th of October proved fatal. He died in the seventy-third year of his age.

Bishop Horsley was a hard student all his life. His active mind was ever directed to some pursuit. He was an acute and original thinker, with a powerful intellect. He was proficient in languages and Scripture criticism, and thus well fitted for controversy. He was naturally warm and uncompromising, and considering the agitated period in which he lived, whether as to church or state, it is no more wonderful that he exhibited at times the heats and asperities of controversy, than it is that his opponents did the same. Though a high churchman, he possessed more true liberality, and understood better the broad principles of practical toleration, than many of his clamorous opponents. His sermons display vigour, depth, precision, originality, and judgment. His patient research and extensive erudition often enable him to render easy a difficult subject.

Besides the works already mentioned, Bishop Horsley was the author of the following, viz.—1. On the Properties of the Greek and Latin Languages, 1795, in 8vo; 2. On the Achronical Rising of the Pleiades, appended to Dr Vincent's Voyage of Noarchus, 1797; 3. A Circular Letter to the Diocese of Rochester, on the Scarcity of Corn, 1796; 4. Another Circular Letter to that Diocese on the Defence of the Kingdom, 1798; 5. Critical Disquisitions on the 18th Chapter of Isaiah, 1799, in 4to; 6. Hosea translated from the Hebrew, with Notes explanatory and critical, 1801, in 4to; 7. Elements, Tracts, and other fundamental principles of Practical Mathematics, for the use of Students, 1801, in 8vo. Since his death have appeared—1. Sermons, 1810 and 1812, in three vols. 8vo; 2. Tracts in controversy with Dr Priestley, upon the historical question of the belief of the first ages in the Divinity of Jesus Christ, revised and augmented by the author, with an Appendix by his Son, 1812, in 8vo; 3. The Speeches in Parliament of Samuel Horsley, 1813; and, 4. The Charges delivered at his several visitations of the dioceses of St David's, Rochester, and St Asaph, 1813, in 8vo.—(Chalmers's Biog. Dict., art. HORSLEY; Edinburgh Review, vol. xvii. p. 465.)