CAVENDISH, Thomas, of Suffolk, the second Englishman who sailed round the globe, was descended from a noble family in Devonshire. Having dissipated his fortune, he resolved to repair it at the expense of the Spaniards. He sailed from Plymouth with two small ships in 1586, passed through the Straits of Magelhaens, took many rich prizes along the coasts of Chili and Peru, and near California possessed himself of the St Ann, an Acapulco ship, with a cargo of immense value. Having completed the circumnavigation of the globe, he returned home round the Cape of Good Hope, and reached Plymouth again in September 1588. On his arrival it is said that his soldiers and sailors were clothed in silk, his sails were damask, and his top-mast was covered with cloth of gold. But his hastily acquired riches did not last long; for in 1591 he had reduced himself to the necessity of [7:6:260]undertaking another voyage, which was far from being so successful as the former. He proceeded no farther than the Straits of Magelhaens, where the weather obliging him to return, he died of grief on the coast of Brazil.

Cavendish, Sir William, descended of an ancient and honourable family, was born about the year 1505, being the second son of Thomas Cavendish of Cavendish in Suffolk, clerk of the pipe in the reign of Henry VIII. Having had a liberal education, he was taken into the family of Cardinal Wolsey, whom he served in the capacity of gentleman-usher of the chamber, wjιen that magnificent prelate maintained the style and dignity of a prince. In 1527 he attended his master on his splendid embassy to France, returned with him to England, and was one of the few who continued faithful to him in his disgrace. Mr Cavendish was with him when he died, and delayed going to court till he had performed the last duty of a faithful servant, by seeing his remains decently interred. The king was so far from disapproving of his conduct, that he immediately took him into his household, made him treasurer of his chamber and a privy counsellor, and afterwards conferred on him the order of knighthood. He was also appointed one of the commissioners for receiving the surrender of religious houses. In 1540 he was nominated one of the auditors of the court of augmentations, and soon afterwards obtained a grant of several considerable lordships in Hertfordshire. In the reign of Edward VI. his estates were much increased by royal grants in seven different counties; and he appears to have continued in high favour at court during the reign of Queen Mary. He died in the year 1557. Sir William was the founder of Chatsworth, and ancestor of the Dukes of Devonshire. He wrote The Life and Death of Cardinal Wolsey, printed at London in 1607.

Cavendish, Margaret, Duchess of Newcastle, famous for her voluminous productions, was born about the latter . end of the reign of James I., and was the youngest sister of Lord Lucas of Colchester. She married the Duke of Newcastle abroad in 1645; and on their return after the restoration, spent the remainder of her life in writing plays and poems, together with the life of her husband, to the amount of about a dozen of folios. “What gives the best idea of her unbounded passion for scribbling,” says Mr Walpole, “was her seldom revising the copies of her works, lest, as she said, it should disturb her following conceptions.” She died in 1673.

Cavendish, William, the first Duke of Devonshire, and one of the most distinguished of British patriots, was born in 1640. In 1677, being then member for Derby, he vigorously opposed the venal measures of the court; and the following year he was one of the committee appointed to draw up articles of impeachment against the lord-treasurer Danby. In 1679, being re-elected to serve for Derby in a new parliament, Charles II. thought proper to make him a privy counsellor; but he soon withdrew from the board with his friend Lord Russell, when he found that the Popish interest prevailed. He carried up the articles of impeachment to the House of Lords against Lord Chief-justice Scroggs, for his arbitrary and illegal proceedings in the court of king’s bench; and when the king declared his resolution not to sign the bill for excluding the Duke of York, afterwards James IL, he moved the House of Commons that a bill might be brought in for the association of all his majesty’s Protestant subjects. He also openly denounced the king’s evil counsellors, and voted for an address to remove them from his presence and councils forever. He nobly appeared at Lord Russell’s trial in defence of that great man, at a time when it was scarcely more criminal to be an accomplice than a witness. The same fortitude, activity, and love of his coun try, animated this illustrious patriot to oppo⅛> the arbitrary’ proceedings of James II.; and when he saw t»at there was no other mode of saving the nation from impending slavery, he was the foremost in the association fir inviting over the Prince of Orange, and the first noblemañwho appeared in arms to receive him at his landing, 'ffe was created Duke of Devonshire in 1694 by William andMary. His last public service was assisting in concluding the union with Scotland, for negotiating of which he had bten appointed a commissioner by Queen Anne. He died h 1707, and ordered the following inscription to be put on his monument:
Willielmus dux Devon,
Bonorum Principum Fidelis Subditus,
Inimicus et Invisus Tyrannis.

Cavendish, Henry, a great and justly celebrated chemist, natural philosopher, and astronomer; son of Lord Charles Cavendish, and grandson of William, second duke of Devonshire; born the lOth of October 1731, at Nice, where his mother, Lady Anne Grey, daughter of Henry duke of Kent, had gone, though ineffectually, for the recovery of her health.

Of a man whose rank among the benefactors of science and of mankind is so elevated as that of Cavendish, we are anxious to learn all the details both of intellectual cultivation and of moral character, which the labours of a biographer can discover and record. Little, however, is known respecting his early education. He was for some time at Newcombe’s school, an establishment of considerable reputation at Hackney, and he afterwards went to Cambridge; but it is probable that he acquired his taste for experimental investigation in a great measure from his father, who was in the habit of amusing himself with meteorological observations and apparatus, and to whom we are indebted for a very accurate determination of the depression of mercury in barometrical tubes, which has been made the basis of some of the most refined investigations of modern times. “It has been observed,” says Μ. Cuvier, “that more persons of rank enter seriously into science and literature in Great Britain than in other countries; and this circumstance may naturally be explained from the constitution of the British government, which renders it impossible for birth and fortune alone to attain to distinction in the state without high cultivation of mind; so that amidst the universal diffusion of solid learning which is thus rendered indispensable, some individuals are always found who are more disposed to occupy themselves in the pursuit of the eternal truths of nature, and in the contemplation of the finished productions of talent and genius, than in the transitory interests of the politics of the day.” Mr Cavendish was neither influenced by the ordinary ambition of becoming a distinguished statesman, nor by a taste for expensive luxuries or sensual gratifications; so that, enjoying a moderate competence during his father’s life, and being elevated by his birth above all danger of being despised for want of greater affluence, he felt himself exempted from the necessity of applying to any professional studies, of courting the approbation of the public either by the parade of literature or by the habits of conviviality, or of ingratiating himself with mixed society by the display of superficial accomplishments. It is difficult to refrain from imagining that his mind had received some slight impression from the habitual recurrence to the motto of his family; the words cavendο tutus must have occurred perpetually to his eyes; and all the operations of his intellectual powers exhibit a degree of caution almost unparalleled in the annals of science; for there is scarcely a single instance in which he had occasion to retrace his steps or to recal his opinions. In 1760 he became a fellow of the Royal Society, and continued [7:6:261]for almost fift; years to contribute to the Philosophical Transactions some of the most interesting and important papers that ∏ave ever appeared in that collection, expressed in language which affords a model of concise simplicity and unaffected modesty, and exhibiting a precision of experimental demonstration, commensurate to the judicious selection of the methods of research, and to the accuracy of the argumentative induction; and which have been considered, by some of the most enlightened historians, as having been no less instrumental in promoting the further progress of chemical discovery, by banishing the vague manner of observing and reasoning that had too long prevailed, than by immediately extending the bounds of human knowledge with respect to the very important facts which are first made public in these communications.

1. Three Papers, containing Experiments on Factitious Air. Phil. Trans. 1766, p. 141. It had been observed by Boyle, that some kinds of air were unfit for respiration; and Hook and Mayow had looked still farther forwards into futurity with prophetic glances, which seem to have been soon lost and forgotten by the inattention or want of candour of their successors. Hales had made many experiments on gases, but without sufficiently distinguishing their different kinds, or even being fully aware that fixed air was essentially different from the common atmosphere. Sir James Lowther, in 1733, had sent to the Royal Society some bladders filled with coal damp, which remained inflammable for many weeks; little imagining the extent of the advantages which were one day to result to his posterity from the labours of that society, by the prevention of the fatal mischiefs which this substance so frequently occasioned. Dr Seip had soon afterwards suggested that the gas which stagnated in some caverns near Pyrmont was the cause of the briskness of the water; Dr Brownrigg of Whitehaven had confirmed this opinion by experiments in 1741; and Dr Black, in 1755, had explained the operation of this fluid in rendering the earths and alkalies mild. Such was the state of pneumatic chemistry when Mr Cavendish began these experimental researches. He first describes the apparatus now commonly used in processes of this kind, a part of which had been before employed by Hales and others, but which he had rendered far more perfect by the occasional employment of mercury. He next relates the experiments by which he found the specific gravity of inflammable air to be about τ 1 τ th of that of common air, whether it was produced from zinc or otherwise: first weighing a bladder filled with a known bulk of the gas, and then in a state of collapse; and also examining the loss of weight during the solution of zinc in an acid, having taken care to absorb all the superfluous moisture of the gas by means of dry potass. He also observed, that the gas obtained during the solution of copper in muriatic acid was rapidly absorbed by water, but he did not inquire further into its nature. The second paper relates to fixed air, which was found to undergo no alteration in its elasticity when kept a year over mercury; to be absorbed by an equal bulk of water, or of olive oil, and by less than half its bulk of spirit of wine; to exceed the atmospheric air in specific gravity by more than one half, and to render this fluid unfit for supporting combustion, even when added to it in the proportion of 1 to 9 only. Mr Cavendish ascertained the quantity of this gas contained in marble and in the alkalies; but his numbers fell somewhat short of those which have been determined by later experiments. He also observed the solubility of the supercarbonate of magnesia. In the third part, the air produced by fermentation and putrefaction is examined. Macbride had shown that a part of it was-fixed air; and our author finds that sugar and water, thrown into fermentation by yeast, emit this gas, without altering the quantity or quality of the common air previously contained in the vessel, which retains its power of exploding with hydrogen, exactly like common air. He also shows that the gas thus emitted is identical with the fixed air obtained from marble; and that the inflammable air extricated during putrefaction resembles that which is procured from zinc, although it appears to be a little heavier.

2. Experiments on Pathhone Place Water. Phil. Trans. 1767, p. 92. In this paper Mr Cavendish shows the solubility of the supercarbonate of lime, which is found in several waters about London, and is decomposed by the process of boiling, the simple carbonate being deposited in the form of a crust. The addition of pure lime water also causes a precipitation of a greater quantity of lime than it contains. These conclusions are confirmed by synthetical experiments, in which the supercarbonate is formed, and remains in solution.

3. An Attempt to explain some of the principal Phenomena of Electricity by means of an Elastic Fluid. Phil. Trans. 1771, p. 584. Our author’s theory of electricity agrees with that which had been published a few years before by Aepinus, but he has entered more minutely into the details of calculation; showing the manner in which the supposed fluid must be distributed in a variety of cases, and explaining the phenomena of electrified and charged substances, as they are actually observed. There is some degree of unnecessary complication, from the great generality of the determinations; the law of electric attraction and repulsion not having been at that time fully ascertained, although Mr Cavendish inclines to the true supposition, of forces varying inversely as the square of the distance. This deficiency he proposes to supply by future experiments, and leaves it to more skilful mathematicians to render some other parts of the theory still more complete. He probably found, that the necessity of the experiments which he intended to pursue was afterwards superseded by those of Lord Stanhope and Μ. Coulomb; but he had carried the mathematical investigation somewhat farther at a later period of his life, though he did not publish his papers; an omission, however, which is the less to be regretted, as Μ. Poisson, assisted by all the improvements of modern analysis, afterwards treated the same subject in a very masterly manner. The acknowledged imperfections in some parts of Mr Cavendish’s demonstrative reasoning, have served to display the strength of a judgment and sagacity still more admirable than the plodding labours of an automatical calculator. One of the corollaries seems at first sight to lead to a mode of distinguishing positive from negative electricity, which is not justified by experiment; but the fallacy appears to be referable to the very comprehensive character of the author’s hypothesis, which requires some little modification to accommodate it to the actual circumstances of the electric fluid, as it must be supposed to exist in nature.

4. A Report of the Committee appointed by the Royal Society to consider of a Method for securing the Powder Magazine at Purfleet. Phil. Trans. 1773, p. 42. Additional Letter, p. 66. Mr Cavendish, and most of his colleagues on the committee, recommended the adoption of pointed conductors; Mr Wilson protested, and preferred blunt conductors; but the committee persisted in their opinion. Later experiments, however, have shown that the point in dispute between them was of little moment.

5. An Account of some Attempts to imitate the Effects of the Torpedo by Electricity. Phil. Trans. 1776, p. 196. The peculiarity of these effects is shown to depend in some measure on the proportional conducting powers of the substances concerned, and on the quantity,of electricity, as distinguished from its intensity. Iron is found to conduct 400 million times as well as pure water, and sea water 720 [7:6:262]times as well; and the path chosen by the electric fluid depending on the nature of all the substances within its reach, an animal not immediately situated in the circuit will often be affected, on account of the facility with which animal substances in general conduct the fluid. The shock of a torpedo, producing a strong sensation, but incapable of being conveyed by a chain, was imitated by the effect of a weak charge of a very large battery; and an artificial torpedo of wood being made part of the circuit, the shock diffused itself very perceptibly through the water in which it was placed; but the experiment succeeded better when the instrument was made of wet leather, which conducts rather better than wood, the battery being more highly charged, in proportion to the increase of conducting power.

6. An Account of the Meteorological Instruments used at the Royal Society’s House. Phil. Trans. 1776, p. 375. Of the thermometers it is observed, that they are adjusted by surrounding the tubes with wet cloths or with steam, and barely immersing the bulbs in the water; since a variation of two or three degrees will often occur, if these precautions are neglected. For the correction of the heights of barometers, we have Lord Charles Cavendish’s table of the depression arising from capillary action. The variation compass was found to exhibit a deviation from the meridian 15' greater in the house of the Royal Society than in an open garden in Marlborough Street; there was also a mean error of about 7 ’ in the indications of the dipping needle; but it was difficult to ascertain the dip, without being liable to an irregularity which often amounted to twice as much.

7. Report of the Committee appointed to consider of the best Method of adjusting Thermometers. Phil. Trans. 1777, p. 816. This paper is signed by Mr Cavendish and six other members, but it is principally a continuation of the preceding. It contains very accurate rules for the determination of the boiling point, and tables for the correction of unavoidable deviations from them; establishing 29∙8 inches as the proper height of the barometer for making the experiment if only steam be employed, and 29∙5 if the ball be dipped in the water; but, with all precautions, occasional variations of half a degree were found in the results.

8. An Account of a New Eudiometer. Phil. Trans. 1783, p. 106. Mr Cavendish was aware of the great difference in the results of eudiometrical experiments with nitrous gas, or nitric oxide, according to the different modes of mixing the elastic fluids; and he justly attributes them to the different degrees of oxygenization of the acid that is formed. But he found that when the method employed was the same, the results were perfectly uniform; and he ascertained in this manner that there was no sensible difference in the constituent parts of the atmosphere under circumstances the most dissimilar; the air of London, with all its fires burning in the winter, appearing equally pure with the freshest breezes of the country. He also observed the utility of the sulphurets of potass and of iron for procuring phlogisticated air; but he does not seem to have employed them as tests of the quantity of this gas contained in a given mixture.

9. Observations on Mr Hutchins’s Experiments for determining the degree of Cold at which Quicksilver freezes. Phil. Trans. 1783, p. 303. In experiments of this kind many precautions are necessary, principally on account of the contraction of the metal at the time of its congelation, which was found to amount to about 1/23d of its bulk; and the results which had been obtained were also found to require some corrections for the errors of the scales, which reduced the degree of cold observed to 39° below the zero of Fahrenheit, or 71° below the freezing point, answering to — 39∙4° of the centesimal
scale
. In speaking of the evolution of heat during
congelation
, he calls it “generated” by the substances; and
observes
in a note, that Dr Black’s hypothesis of capacities
depends
“on the supposition that the heat of bodies is owing to
their
containing more or less of a substance called the
matter
of heat; and as” he thinks “Sir Isaac Newton’s
opinion
that heat consists in the internal motion of the particles
of
bodies, much the most probable,” he chooses “to use
the
expression heat is generated,” in order to avoid the
appearance
of adopting the more modern hypothesis; and this persuasion of the non-existence of elementary heat he repeats in his next paper. It is remarkable that one of the first of Sir Humphry Davy’s objects, at the very beginning of his singularly brilliant career of refined investigation and fortunate discovery, was the confirmation of this almost forgotten opinion of Mr Cavendish; and for this purpose lie devised the very ingenious experiment of melting two pieces of ice by their mutual friction in a room below the freezing temperature, which is certainly incompatible with the common doctrine of caloric, unless we admit that caloric could have existed in the neighbouring bodies in the form of cold, or of something else that could be converted into caloric by the operation; and this transmutation would still be nearly synonymous with generation in the sense here intended. However this may be, it is certain that, notwithstanding all the experiments of Count Rumford, Dr Haldalt, and others, Sir Humphry was less successful in persuading his contemporaries of the truth of Mr Cavendish’s doctrine of heat, than in establishing the probability of his opinions respecting the muriatic acid.

10. Experiments on Air. Phil. Trans. 1784, p. 119. This paper contains an account of two of the greatest discoveries in chemistry that have ever yet been made public; the composition of water, and that of the nitric acid. The author first establishes the radical difference of hydrogen from nitrogen or azote; he then proceeds to relate his experiments on the combustion of hydrogen with oxygen, which had partly been suggested by a cursory observation of Mr Warltire, a lecturer on natural philosophy, and which prove that pure water is the result of the process, provided that no nitrogen be present. These experiments were first made in 1781, and were then mentioned to Dr Priestley; and when they were first communicated to Lavoisier, he found some difficulty in believing them to be accurate. The second series of experiments demonstrates, that when phlogisticated air, or nitrogen, is present in the process, some nitric acid is produced; and that this acid may be obtained from atmospheric air, by the repeated operation of the electrical spark.

It has been supposed by one of Mr Cavendish’s biographers, that if Mr Kirwan, instead of opposing, had adopted his chemical opinions, “he would never have been obliged to yield to his French antagonists, and the antiphlogistic theory would never have gained ground.” But in this supposition there seems to be a little of national prejudice. Mr Cavendish by no means dissented from the whole of the antiphlogistic theory; and in this paper he has quoted Lavoisier and Scheele in terms of approbation, as having suggested the opinion “that dephlogisticated and phlogisticated air are quite distinct substances, and not differing only in their degree of phlogistication, and that common air is a mixture of the two.” He afterwards mentions several memoirs of Lavoisier in which phlogiston is entirely discarded; and says that “not only the foregoing experiments, but most other phenomena of nature, seem explicable as well, or nearly as well, upon this as upon the commonly believed principle of phlogiston and after stating a slight conjectural objection, derived from the chemical constitution[7:6:263] of vegetables, he proceeds finally to observe, that “Lavoisier endeavours to prove that dephlogisticated air is the acidifying principle.” This is no more than saying that acids lose their acidity by uniting to phlogiston, which, with regard to the nitrous, vitriolic, phosphoric, and arsenical acids, is certainly true; and probably with regard to the acid of sugar; “but as to the marine acid, and acid of tartar, it does not appear that they are capable of losing their acidity by any union with phlogiston;” and the acids of sugar and tartar become even less acid by a further de-ρhlogistication. It is obvious that this argument amounts only to an exception, and not to a total denial of the truth of the theory. Μ. Cuvier has even asserted that the antiphlogistic theory derived its first origin from one great discovery of Mr Cavendish, that of the nature of hydrogen gas, and owed its complete establishment to another, that of the composition of water; but it would be unjust to deny to Lavoisier the merit of considerable originality in his doctrines respecting the combinations of oxygen; and however he may have been partly anticipated by Hook and Mayow, it was certainly from him that the modern English chemists immediately derived the true knowledge of the constitution of the atmosphere, which they did not admit without some hesitation, but which they did ultimately admit when they found the evidence irresistible. On the other hand, it has been sufficiently established, since Mr Cavendish’s death, by the enlightened researches of the most original of all chemists, that Lavoisier had carried his generalization too far; and it must ever be remembered, to the honour of Mr Cavendish, and to the credit of this country, that we had not all been seduced, by the dazzling semblance of universal laws, to admit facts as demonstrated which were only made plausible by a slight and imperfect analogy.

11. Ansiver to Mr Kirwans Remarks upon the Experiments on Air. Phil. Trans. 1784, p. 170. Mr Kirwan, relying on the results of some inaccurate experiments, had objected to those conclusions which form the principal basis of the antiphlogistic theory. Mr Cavendish repeated such of these experiments as seemed to be the most ambiguous, and repelled the objections; showing, in particular, that when fixed air was derived from the combustion of iron, it was only to be referred to the plumbago shown by Bergmann to exist in it, which was well known to be capable, in common with other carbonaceous substances, of affording fixed air.

12. Experiments on Air. Phil. Trans. 1785, p. 372. The discovery of the composition of the nitric acid is here further established; and it is shown that the whole, or very nearly the whole, of the irrespirable part of the atmosphere is convertible into this acid when mixed with oxygen, and subjected to the operation of the electric spark; the fixed air sometimes obtained during the process being wholly dependent on the presence of some organic substances.

13. An Account of Experiments made by Mr John Macnab, at Henley House, Hudson’s Bay, relating to Freezing Mixtures. Phil. Trans. 1786, p. 241. From these experiments Mr Cavendish infers the existence of two distinct species of congelation in mixed liquids, which he calls the aqueous and spirituous congelations, and of several alternations of easy and difficult congelation when the strength is varied, both in the case of the mineral acids and of spirit of wine. The greatest degree of cold obtained in these experiments was — 78½°.

14. An Account of Experiments made by Mr John Macnab, at Albany Fort, Hudson s Hay. Phil. Trans. 1788, p. 166. The points of easy congelation are still further investigated, and illustrated by comparison with Mr Keir’s experiments on the sulphuric acid. It was found that the nitric acid was only liable to the aqueous congelation, unless it was strong enough to dissolve one fourth of its weight of marble; and that it had a point of easy congelation, when it was capable of dissolving 415/1000, the frozen part exhibiting, in other cases, a tendency to approach to this standard. Mr Keir had found that sulphuric acid of the specific gravity I∙78 froze at 46°; and that it had another minimum when it was very highly concentrated.

15. On the Conversion of a Mixture of Dephlogisticated and Phlogisticated Air into Nitrous Acid, by the Electric Shock. Phil. Trans. 1788, p. 261. Some difficulties having occurred to the Continental chemists in the repetition of this experiment, it was exhibited with perfect success, by Mr Gilpin, to a number of witnesses. This was an instance of condescension which could scarcely have been expected from the complete conviction which the author of the discovery must have felt of his own accuracy, and of the necessity of the establishment of his discovery, when time should have been afforded for its examination.

16. On the Height of the Luminous Arch which ινas seen on Feb. 23, 1784. P/«7. Trans. 1790, p. 101. Mr Cavendish conjectures that the appearance of such arches depends on a diffused light, resembling the aurora borealis, spread into a flattened space contained between two planes nearly vertical, and only visible in the direction of its breadth, so that they are never seen at places far remote from the direction of the surface; and hence it is difficult to procure observations sufficiently accurate for determining their height upon so short a base; but in the present instance there is reason to believe that the height must have been between fifty-two and seventy-one miles.

17. On the Civil Year of the Hindoos, and its Divisions, with an Account of three Almanacs belonging to Charles Wilkins, Esq. Phil. Trans. 1792, p. 383. The subject of this paper is more intricate than generally interesting; but it may serve as a specimen of the diligence which the author employed in the investigation of every point more or less immediately connected with his favourite objects. The month of the Hindus is lunar in its duration, but solar in its commencement; and its periods are extremely complicated, and often different for different geographical situations. The day is divided and subdivided sexagesimally. The date of the year, in the epoch of the Kaly Yug, expresses the ordinal number of years elapsed, as it is usual with our astronomers to reckon their days; so that the year 100 would be the beginning of the second century, and not the 100th year, or the end of the first century, as in the European calendar; in the same manner as, in astronomical language, 1817 December 31d. 18h. means six o’clock in the morning of the 1st of January 1818.

18. Experiments to determine the Density of the Earth. Phil. Trans. 1798, p. 469. The apparatus with which this highly important investigation was conducted had been invented and constructed many years before by the reverend John Michell, who did not live to perform the experiments for which he intended it. Mr Cavendish, however, by the accuracy and perseverance with which he carried on a course of observations of so delicate a nature, as well as by the skill and judgment with which he obviated the many unforeseen difficulties that occurred in its progress, and determined the corrections of various kinds which it was necessary to apply to the results, has deserved no less gratitude from the cultivators of astronomy and geography than if the idea had originally been his own. The method employed was to suspend by a vertical wire a horizontal bar, having a leaden weight at each end; to determine the magnitude of the force of torsion by the time occupied in the lateral vibrations of the bar; and to measure the extent of the change produced in its [7:6:264] situation by the attraction of two large masses of lead placed on opposite sides of the case containing the apparatus, so that this attraction might be compared with the weight of the balls, or, in other words, with the attraction of the earth. In this manner the mean density of the earth was found to be five and a half times as great as that of water; and although this is considerably more than had been inferred from Dr Maskelyne’s observations on the attraction of Shichallain, yet the experiments agree so well with each other, that we can scarcely suppose any material error to have affected them. Mr Michell’s apparatus resembled that which M. Coulomb had employed in his experiments on magnetism, but he appears to have invented it some time before the publication of M. Coulomb’s Memoirs.

19. On an improved Method of Dividing Astronomical Instruments. Phil. Trans. 1809, p. 221. The merits of this improvement have not been very highly appreciated by those who are in the habit of executing the divisions of circular arcs. It consists in a mode of employing a microscope, with its cross wires, as a substitute for one of the points of a beam compass, while another point draws a faint line on the face of the instrument in the usual manner. The Duke de Chaulnes had before used microscopal sights for dividing circles, but his method more nearly resembled that which has been brought forward in an improved form by Captain Kater; and Mr Cavendish, by using a single microscope only, seems to have sacrificed some advantages which the other methods appear to possess; but none of them has been very fairly tried; and our artists have hitherto continued to adhere to the modes which they had previously adopted, and which it would perhaps have been difficult for them to abandon, even if they had been convinced of the advantages to be gained by some partial improvements.

Such were the diversified labours of a philosopher who possessed a clearness of comprehension, and an acuteness of reasoning, which had been the lot of very few of his predecessors since the days of Newton. Maelaurin and Waring, perhaps also Stirling and Landen, were incomparably greater mathematicians; but none of them attempted to employ their powers of investigation in the pursuit of physical discovery. Euler and Lagrange on the Continent had carried the improvements of analytical reasoning to an unparalleled extent; and they both, as well as Daniel Bernoulli and D’Alembert, applied these powers with marked success to the solution of a great variety of problems in mechanics and in astronomy. But they made no experimental discoveries of importance; and the splendid career of chemical investigation which has since been pursued with a degree of success unprecedented in history, may be said to have been first laid open to mankind by the labours of Mr Cavendish; although the further discoveries of Priestley, Scheele, and Lavoisier, soon furnished, in rapid succession, a superstructure commensurate to the extent of the foundations so happily laid. “Whatever the sciences revealed to Mr Cavendish,” says Cuvier, “appeared always to exhibit something of the sublime and the marvellous; he weighed the earth; he rendered the air navigable; he deprived water of the quality of an element and he denied to fire the character of a substance. “The clearness of the evidence on which he established his discoveries, new and unexpected as they were, is still more astonishing than the facts themselves which he detected; and the works in which he has made them public are so many masterpieces of sagacity and of methodical reasoning, each perfect as a whole and in its parts, and leaving nothing for any other hand to correct, but rising in splendour with each successive year that passes over them, and promising to carry down his name to a posterity far more remote than his rank and connections could ever have enabled him to attain without them.”

In his manners Mr Cavendish had the appearance of a quickness and sensibility almost morbid, united tea slight hesitation in his speech, which seems to have depended more on the constitution of his mind than on any deficiency of his organic powers, and to an air of timidity and reserve, which sometimes afforded a contrast, almost ludicrous, with the sentiments of profound respect which were professed by those with whom he conversed. It is not impossible that he may have been indebted to his love of severe study, not only for the decided superiority of his faculties to those of the generality of mankind, but even for his exemption from absolute eccentricity of character. His person was tall, and rather thin; his dress was singularly uniform, although sometimes a little neglected. His pursuits were seldom interrupted by indisposition; but he suffered occasionally from calculous complaints. His retired habits of life, and his disregard of popular opinion, appear to have lessened the notoriety which might otherwise have attached to his multiplied successes in science; but his merits were more generally understood on the Continent than in this country, although it was not till he had passed the age of seventy that he was made one of the eight foreign associates of the institute of France.

Mr Cavendish was not less remarkable, in the latter part of his life, for the immense accumulation of his pecuniary property, than for his intellectual and scientific treasures. His father died in 1783, being at that time eighty years old, and the senior member of the Royal Society; but he is said to have succeeded at an earlier period to a considerable inheritance left him by one of his uncles. He resided principally at Clapham Common; but his library was latterly at his house in Bedford Square; and his books were at the command of all men of letters, either personally known to him, or recommended by his friends; indeed the whole arrangement was so impartially methodical, that he never took down a book for his own use, with≈ out entering it in the loan book; and after the death of a German gentleman, who had been his librarian, he appointed a day on which he attended in person to lend any work for the accommodation of the few who thought themselves justified in applying to him for such books as they wished to consult. He was constantly present at the meetings of the Royal Society, as well as at the conversations held at the house of the president; and he dined every Thursday with the club composed of its members. He had little intercourse with general society, or even with his own family, and saw only once a year the person whom he had made his principal heir. He is said to have assisted several young men whose talents recommended them to his notice, in obtaining establishments in life; but in his later years such instances were certainly very rare. His tastes and his pleasures do not seem to have been in unison with those which are best adapted to the generality of mankind; and amidst the abundance of all the means of acquiring every earthly enjoyment, he must have wanted that sympathy which alone is capable of redoubling our delights, by the consciousness that we share them in common with a multitude of our friends, and of enhancing the beauties of all the bright prospects that surround us, when they are still more highly embellished by reflection “from looks that we love.” He could have had no limitation either of comfort or of luxury to stimulate him to exertion; even his riches must have deprived him of the gratification of believing, that each new triumph in science might promote the attainment of some great object in life that he earnestly desired; a gratification generally indeed illusory, but which does not cease to beguile us till we become callous[7:6:265] as well to the pleasures as to the sorrows of existence. But in midst of this “painful pre-eminence,” he must still have been capable of extending his sensibility over a still wider field of time and space, and of looking forward to the approbation of the wise and the good of all countries and of all ages; and he must have enjoyed the highest and purest of all intellectual pleasures, arising from the consciousness of his own excellence, and from the certainty that, sooner or later, all mankind must acknowledge his claim to their profoundest respect and highest veneration.

“It was probably either the reserve of his manners,” says Cuvier, “or the modest tone of his writings, that procured him the uncommon distinction of never having his repose disturbed either by jealousy or by criticism. Like his great countryman Newton, whom he resembled in so many other respects, he died full of years and honours, beloved even by his rivals, respected by the age which he had enlightened, celebrated throughout the scientific world, and exhibiting to mankind a perfect model of what a man of science ought to be, and a splendid example of that success which is so eagerly sought, but so seldom obtained.” The last words that he uttered were characteristic of his unalterable love of method and subordination; he had ordered his servant to leave him, and not to return till a certain hour, intending to pass his latest moments in the tranquillity of perfect solitude; but the servant’s impatience to watch his master diligently having induced him to infringe the order, he was severely reproved for his indiscretion, and took care not to repeat the offence until the scene was finally closed. Mr Cavendish died on the 24th of February 1810, and was buried in the family vault at Derby. He left a property in the funds of about L.700,000, which he divided into six equal parts, giving two to Lord George Cavendish, the son of his first cousin, one to each of his sons, and one to the Earl of Bessborough, whose mother was also his first cousin. Some other personal property devolved to Lord George as residuary legatee; and a landed estate of L.6000 a year descended to his only brother, Mr Frederic Cavendish of Market Street, Herts, a single man, and of habits of life so peculiarly retired, that any further increase of income would have been still more useless to him than it had been to the testator.

Much as Mr Cavendish effected for the promotion of physical science throughout his life, it has not been unusual, even for his warmest admirers, to express some regret that he did not attempt to do still more after his death by the appropriation of a small share of his immense and neglected wealth to the perpetual encouragement of those objects which he had himself pursued with so much ardour. But however we might be disposed to lament such an omission, we have surely no reason to complain of his determination to follow more nearly the ordinary course of distribution of his property, among those whose relationship would have given them a legal claim to the succession if he had not concerned himself in directing it. We may observe on many other occasions that the most successful cultivators of science are not always the most strenuous promoters of it in others; as we often see the most ignorant persons, having been rendered sensible by experience of their own deficiencies, somewhat disposed to overrate the value of education, and to bestow more on the improvement of their children than men of profounder learning, who may possibly have felt the insufficiency of their own accomplishments for insuring success in the world. But even if Mr Cavendish had been inclined to devote a large share of his property to the establishment of fellowships or professorships, for the incitement of men of talents to a more complete devotion of their lives to the pursuit of science, it is very doubtful whether he could have entertained a reasonable hope of benefiting his country by such an institution; for the highest motives that stimulate men to exertion are not those which are immediately connected with their pecuniary interests. The senators and the statesmen of Great Britain are only paid in glory; and where we seek to obtain the co-operation of the best educated and the most enlightened individuals in any pursuit or profession, we must hold out as incentives the possession of high celebrity and public respect, assured that they will be incomparably more effectual than any mercenary considerations, which are generally found to determine a crowd of commercial speculators to enter into competition for the proposed rewards, and to abandon all further concern with the objects intended to be pursued as soon as their avarice is gratified. To raise the rank of science in civil life is therefore most essentially to promote its progress; and when we compare the state not only of the scientific associations, but also of the learned professions, in this country and among our neighbours, we shall feel little reason to regret the total want of pecuniary patronage that is remarkable in Great Britain with respect to every independent department of letters, while it is so amply compensated by the greater degree of credit and respectability attached to the possession of successful talent. It must not however be denied, that even in this point of view there might be some improvement in the public spirit of the country. Mr Cavendish was indeed neither fond of giving nor of receiving praise; and he was little disposed to enliven the intervals of his serious studies by the promotion of social or convivial cheerfulness; but it would at all times be very easy for an individual, possessed of high rank and ample fortune, of correct taste and elegant manners, to confer so much dignity on science and literature, by showing personal testimonies of respect to acknowledged merit, as greatly to excite the laborious student to the unremitting exertions of patient application, and to rouse the man of brilliant talent to the noblest flights of genius. (l. l.)