MacTutor
Edward Troughton was born, it is believed, in October 1753, in the parish of Corney, on the south-west coast of the county of Cumberland, the third son of a small farmer, who was also, in the language of that country, a statesman. An uncle of the same name, and his eldest brother, John, were settled in London as mathematical instrument makers; and, as his second brother was apprenticed to the same business, Edward was designed to be a farmer, and continued to be his father's assistant till the age of seventeen. To persons acquainted with the condition of that part of England, it need not be said that his education was better than is usual for his rank, and was of a sound though homely cast.
There has always been there, so far as memory goes back, a considerable stock of mathematical and general knowledge floating amongst the people; and a large proportion of persons distinguished for their attainments in the university of Cambridge have arisen among the Cumberland and Westmoreland yeomanry. The death of his preceding brother altered Edward's destination, and he was placed with his brother John, then a chamber-master, employed chiefly in dividing and engraving for the trade and the higher branches of the art. Under the instruction of his brother, who was an excellent workman, Troughton made most rapid progress, and at the expiration of his time was admitted as a partner. About 1782, the Troughtons established themselves in Fleet Street, where they commenced an independent business as successors to a series of well-known artists (Wright, and subsequently Cole), who had previously occupied the same premises. Ramsden was then in the zenith of his reputation, but his dilatory habits were little suited to the wants and impatience of astronomers; and this, and their own intrinsic merits, speedily advanced the brothers in their profession, and in the estimation of competent judges. Considerable rivalry ensued, and Edward Troughton, who felt his own powers, was not a person to conceal his feelings or to propitiate an adversary. After the death of his brother John, Edward alone continued the business, latterly at a loss rather than a profit, till 1826, when his increasing age and dislike to routine employment induced him to take Mr. William Simms as his partner and successor. Mr. Troughton died at his house in Fleet Street, June 12, 1835, in the eighty-second year of his age, and was buried according to his request at the Cemetery, Kensell Green. Many of the members of this Society paid their tribute of respect to his memory by attending his funeral.
An admirable marble bust of Troughton, by Chantrey, was executed some years before his death, at the expense of his private friends and admirers. This is placed, as he wished it to be, in the Royal Observatory, Greenwich.
The life of an artist is generally contained in the history of his works, and this is peculiarly true of Mr. Troughton. Of him it may be said with truth, that he improved and extended the use of every instrument he touched, and that every astronomical instrument was in its turn the subject of his attention. In this branch he has perhaps no equal, except the celebrated Graham, the object of his unbounded admiration. To describe all his improvements or inventions would require a detailed account of almost every instrument, astronomical, nautical, or geodesical, in actual use; and we must therefore limit this notice to a brief and very imperfect summary.
The instruments which facilitate navigation were peculiarly objects of interest to Mr. Troughton; and long after his infirmities were an effectual bar to the applications of his most esteemed friends, he exerted himself to supply the seamen with well-adjusted and accurate sextants. "Your fancies," he would say, "may wait; their necessities cannot." In 1788 he took out a patent for the double-framed sextant, a construction which, combining firmness and lightness, yet admitted of a considerable radius in this invaluable instrument. In the adjustments of his sextants, and in the selection of their mirrors and glasses, he was most careful, and for many years scarcely any other were seen in the hands of the most scientific navigators of our own or foreign navies. But there is a fault in the construction of the sextant, which the maker can only imperfectly guard against that of a sensible excentricity; and the detection and correction of this, though not very difficult, is beyond the skill of ordinary observers. After trying and rejecting the repeating reflecting circle of Borda, Mr. Troughton (1796) hit upon one of his happiest constructions, the British reflecting circle, as he delighted to call it an instrument which, in right hands, is capable of wonderful accuracy. The additional weight of the circle, and the trouble of the extra readings, have hitherto prevented its introduction into common use, and perhaps at sea, where the errors of observation are necessarily of as large an order as those of a good sextant, the superior accuracy of the circle may not come into play; but for observations on shore and with a stand, no sensible observer can hesitate between the instruments. It is a characteristic trait of Mr. Troughton, that in order to bring his favourite circle into general use, he reduced its price far below the usual profits of trade; and if he had succeeded in his attempt he might have been ruined by his success, for his sextants were by much the most gainful article of his business. With the same earnestness to promote navigation he invented the dip sector (afterwards reinvented by Dr. Wollaston), and expended time, money, and ingenuity to no inconsiderable amount, in attempting to perfect the marine top for producing a true horizontal reflecting surface at sea. The marine barometer, the snuff-box sextant, and the portable universal dial, owe to him all their elegance, and much of their accuracy. Where others invented or sketched, he perfected.
In the ordinary physical apparatus, he made considerable improvement in the construction of the balance, and of the mountain barometer. In the same class may be mentioned, the form given to the compensated mercurial pendulum; his pyrometer, by which some very valuable expansions have been determined; the apparatus by which Sir George Shuckburgh attempted to ascertain the standard of weight and measure; and that which, in the hands of Mr. Baily, has given an invariable simple seconds pendulum. On the length of the simple pendulum Mr. Troughton himself made many very careful and extensive experiments, according to views and after a procedure of his own; but his ideas, though ingenious and elegant, were not pursued after Captain Kater's happy application of Huyghen's theorem. The apparatus for determining the Standard Scale of this Society is noticed in the present Report, and described in Mr. Baily's memoir. In the ordinary geodesical instruments Mr. Troughton greatly improved the surveying level and staff, and reduced them both in weight and price with increased convenience and accuracy. The errors of the common surveying chain, which are sometimes enormous, and the complexity and expense of that made by Ramsden for the trigonometrical survey, led to the construction of a more simple and accurate chain, at a reasonable cost and of easy use. The larger theodolites by Mr. Troughton, those for instance of twelve inches diameter, are remarkable for simplicity and power. In the refined and delicate instruments which have been applied to the most accurate geodesical measurements, we may mention the large theodolite for the American coast survey (1815), and those for the Irish (1822) and for the Indian surveys (1830), which may be advantageously contrasted, for their design and simplicity, with those, however otherwise excellent, of Ramsden; and also the apparatus for measuring a base line (1827), employed by Colonel Colby in Ireland, and Colonel Everest in India (1829). It must not, however, be forgotten, that the idea of this last most exquisite apparatus, and very much of the novelty of the construction, are due to our excellent members, Colonel Colby and Lieutenant Drummond. Mr. Troughton made some very beautiful and manageable zenith sectors, which were capable of great accuracy, considering their dimensions: one of these is, we believe, in the possession of the Danish government, and was employed in the Holstein survey by Professors Schumacher and Gauss. He had designed one for America on the same construction, with a six-feet telescope and arc, but it was never completed, though considerable progress had been made.
It is, however, more properly with the astronomical instruments of this great artist that we are immediately concerned; and here he reigns without a rival. His portable astronomical quadrants are models of strength and lightness. In the small altitude and azimuth circle (1792), the portable transit, and the portable universal equatorial, it is not easy to state accurately the line between his improvements or inventions, and those of preceding artists; but it is from him that these instruments received their present form and perfection. The repeating circle of Borda, an instrument which he disliked, first received its beauty and accuracy from his hands; and for it he invented his very elegant double-foot screw, to give minute adjustments. The ordinary reading micrometer, and the position micrometer commonly employed in the measurement of double stars, were greatly improved by him in simplicity and brought to perfection; and he first applied the former to dividing, though in circles and scales it had already been used in the reading off. In the class of larger altitude circles, revolving freely in azimuth, we find the circle for Count Bruhl (1792), the Westbury circle (1806), that for Sir T. M. Brisbane, the Society's Lee circle, the substance and form of Dr. Pearson's circle, those employed in the Indian survey for determining latitudes (1830), and that at the Edinburgh observatory (1830), with many others which it would be tedious to mention. In Groombridge's transit circle (1806), the beauty of the form and accuracy of the divisions satisfied every body but the artist himself, whose experience and matured powers were finally exhibited in the mural circle. This finished specimen of sound engineering and mechanical construction at first met with much opposition; and many were the objections, both before and after the erection of the Greenwich mural (1812), with which its inventor was assailed. To these he resolutely turned a deaf ear, for nothing could shake his confidence in what he knew; and he had the pleasure of finding, before his death, the mural circle established not only at the Royal Observatory of Paris, but also at the Cape, St. Helena, Madras, Cracow (1832), Edinburgh (1834), Brussels (1835), Cadiz, Armagh, and Cambridge (1832). A small model, of two feet in diameter, was made for Sir T. M. Brisbane prior to the Greenwich mural, and is now at the observatory of Paramatta. The principal equatorial instruments of Mr. Troughton, with accurately divided circles, are those of Coimbra (1788), Armagh and Brussels (1834). When we add to this long catalogue the large transits at Greenwich (1816), Camden Hill (1820), Cracow (1828), Markrea (1832), &c., in which the differential screws are so beautifully applied to form what he called the bones of the instrument, and the gigantic zenith tube at Greenwich, which he just finished before his strength failed, we have reason to wonder that even his long and active life should have sufficed for works of such variety and extent, and may form some estimate of the value of Mr. Troughton's labours, and their effect on modern astronomy. It may, perhaps, be remarked, that the only astronomical instrument which is not greatly indebted to Mr. Troughton is the telescope; and he was deterred from any attempt in this branch of his art, by a singular physical defect, which existed in many members of his family. He could not distinguish colours, and had little idea of them, except generally as they conveyed the idea of greater or less light. The ripe cherry and its leaf were to him of one hue, only to be distinguished by their form; and he was in the habit of relating some curious mistakes committed by himself, and others of his relations, in confounding green and red. With this defect in his vision, he never attempted any experiments in which colour was concerned; and it is difficult to see how he could have done so with success.
The most remarkable of Mr. Troughton's writings are, "An account of a method of dividing astronomical and other instruments by ocular inspection," &c., printed in the Phil. Trans. 1809, which was rewarded with the Copley medal; "A comparison of the repeating circle of Borda with the altitude and azimuth circle," in the Ist volume of this Society's Memoirs; and several articles in Brewster's Edinburgh Encyclopædia, such as "Circle," "Graduation," &c. The descriptions of instruments of his invention or construction, may generally be considered to have been furnished by him to the authors of the articles in which they appear; and an experienced judge will easily distinguish by the peculiar conciseness of his style (for he wrote in the same spirit as he constructed), the cases, and also the extent, to which this remark applies. His method of dividing has been generally adopted, and with the obvious modification of dividing by diameters instead of radii, so as to eliminate any defect in the turning of the collar or rim, has not received, and seems scarcely to require, any further improvement. In 1825, Mr. Troughton paid a visit to Paris, where he was received with great cordiality and respect by the distinguished artists and men of science of that metropolis. In 1830, he received an honorary gold medal from his majesty the King of Denmark.
Mr. Troughton was one of the original members of this Society, and at all times sincerely anxious for its prosperity. So long as his health permitted, he continued to be a constant attendant, notwithstanding his deafness, on the meetings of the council, and the ordinary meetings of the Society; and his valuable assistance and advice were most readily afforded whenever they were required. His singularly clear understanding, his unimpeachable integrity, and kind, though independent temper, made him universally respected; and there was an originality and raciness in his conversation and anecdotes rarely to be met with. At times, his criticisms might be considered to be severe, but never unfair, except, perhaps, on his ancient antagonist Ramsden, against whom he fancied he had grounds for complaint. In every other instance he was as ready to praise as to censure, and gave full and hearty approbation to the masterly conceptions of Graham, the beautiful execution of Bird, and the ingenuity and fertile invention of Ramsden himself. Nor was he niggardly towards his contemporaries and juniors. It may be added, that notwithstanding his high reputation and very simple habits, his carelessness of money did not allow him to become rich, for his object was fame rather than wealth. The following are references to the books in which Troughton's principal instruments are described :-
British Reflecting Circle. Brewster's Encyclopædia, vol. vi. p. 488. Plates CXLIV. V.
Nautical Top. Brewster's Encyclopædia, vol. xviii. p. 70. Sir G. E. Shuckburgh's Scale and Apparatus. Phil. Trans. 1798, p. 133, Plates v. VI . VIL.
Mr. Baily's Pendulum. Phil. Trans. 1832, p. 403.
Astronomical Society's Scale, &c. Mr. Baily's Report, &c. Mem. Royal Ast. Soc. vol. ix.
Portable Zenith Sector. Pearson's Pract. Astron., vol. ii. p. 546. Plate XXXII.
Astronomical Quadrant. Brewster's Encyclopædia, vol. ii. p. 725. Plate XLV.
Astronomical Quadrant. Pearson's Pract. Astron., vol. ii. p. 555. Plate XXIX.
Portable Altitude and Azimuth. Brewster's Encyclopædia, vol. vi. p. 492. Plate CXLVI.
Borda's Repeating Circle. Brewster's Encyclop., vol. vi. p. 498. Plate CXLVII.
For these two instruments, see Mr. Troughton's Memoir in the 1st volume of the Astronomical Society's Memoirs.
Position Micrometer. Pearson's Pract. Ast., vol. ii. p. 99. Plate x1. figs. 1, 2, 3.
Westbury Circle. Pisil. Trans. 1006, p. 420. Plate xx.
Sir T. M. Brisbane's Circle. Brewster's Encyclop., vol. ii. p. 727. Plate XLVI.
Pearson's Circle. Pearson's Practical Astronomy, vol. ii. p. 434. Plate XIX.
This circle was divided by Mr. Thomas Jones by Mr. Troughton's method. Groombridge's Transit Circle. Pearson's Practical Astronomy, vol. ii. p. 402. Plate XVII.
Mural Circle. Plate in Pond's Observations, vol. i.; Pearson's Practical As. tronomy, vol. ii. p. 472, Plate xx., but no detailed description of the instru-ment has yet appeared. The circles of Edinburgh, Brussels, Cracow, and Cambridge, are by Messrs. Troughton and Simms.
Coimbra Equatorial. Pearson's Pract. Astronomy, vol. ii. p. 519. Plate xxv.
Armagh Equatorial. Rees' Cyc., vol. xiii. Art. "Equatorial;" Plate XVI., Astron. Instr. Transact. Royal Irish Academy, vol. xv. p. 1.
Greenwich Transit. Pearson's Pract. Astronomy, vol. ii. p. 366. Plate XVI.
Camden Hill Transit. Phil. Trans. 1826, p. 423. Plates XVI., XVII.
There has always been there, so far as memory goes back, a considerable stock of mathematical and general knowledge floating amongst the people; and a large proportion of persons distinguished for their attainments in the university of Cambridge have arisen among the Cumberland and Westmoreland yeomanry. The death of his preceding brother altered Edward's destination, and he was placed with his brother John, then a chamber-master, employed chiefly in dividing and engraving for the trade and the higher branches of the art. Under the instruction of his brother, who was an excellent workman, Troughton made most rapid progress, and at the expiration of his time was admitted as a partner. About 1782, the Troughtons established themselves in Fleet Street, where they commenced an independent business as successors to a series of well-known artists (Wright, and subsequently Cole), who had previously occupied the same premises. Ramsden was then in the zenith of his reputation, but his dilatory habits were little suited to the wants and impatience of astronomers; and this, and their own intrinsic merits, speedily advanced the brothers in their profession, and in the estimation of competent judges. Considerable rivalry ensued, and Edward Troughton, who felt his own powers, was not a person to conceal his feelings or to propitiate an adversary. After the death of his brother John, Edward alone continued the business, latterly at a loss rather than a profit, till 1826, when his increasing age and dislike to routine employment induced him to take Mr. William Simms as his partner and successor. Mr. Troughton died at his house in Fleet Street, June 12, 1835, in the eighty-second year of his age, and was buried according to his request at the Cemetery, Kensell Green. Many of the members of this Society paid their tribute of respect to his memory by attending his funeral.
An admirable marble bust of Troughton, by Chantrey, was executed some years before his death, at the expense of his private friends and admirers. This is placed, as he wished it to be, in the Royal Observatory, Greenwich.
The life of an artist is generally contained in the history of his works, and this is peculiarly true of Mr. Troughton. Of him it may be said with truth, that he improved and extended the use of every instrument he touched, and that every astronomical instrument was in its turn the subject of his attention. In this branch he has perhaps no equal, except the celebrated Graham, the object of his unbounded admiration. To describe all his improvements or inventions would require a detailed account of almost every instrument, astronomical, nautical, or geodesical, in actual use; and we must therefore limit this notice to a brief and very imperfect summary.
The instruments which facilitate navigation were peculiarly objects of interest to Mr. Troughton; and long after his infirmities were an effectual bar to the applications of his most esteemed friends, he exerted himself to supply the seamen with well-adjusted and accurate sextants. "Your fancies," he would say, "may wait; their necessities cannot." In 1788 he took out a patent for the double-framed sextant, a construction which, combining firmness and lightness, yet admitted of a considerable radius in this invaluable instrument. In the adjustments of his sextants, and in the selection of their mirrors and glasses, he was most careful, and for many years scarcely any other were seen in the hands of the most scientific navigators of our own or foreign navies. But there is a fault in the construction of the sextant, which the maker can only imperfectly guard against that of a sensible excentricity; and the detection and correction of this, though not very difficult, is beyond the skill of ordinary observers. After trying and rejecting the repeating reflecting circle of Borda, Mr. Troughton (1796) hit upon one of his happiest constructions, the British reflecting circle, as he delighted to call it an instrument which, in right hands, is capable of wonderful accuracy. The additional weight of the circle, and the trouble of the extra readings, have hitherto prevented its introduction into common use, and perhaps at sea, where the errors of observation are necessarily of as large an order as those of a good sextant, the superior accuracy of the circle may not come into play; but for observations on shore and with a stand, no sensible observer can hesitate between the instruments. It is a characteristic trait of Mr. Troughton, that in order to bring his favourite circle into general use, he reduced its price far below the usual profits of trade; and if he had succeeded in his attempt he might have been ruined by his success, for his sextants were by much the most gainful article of his business. With the same earnestness to promote navigation he invented the dip sector (afterwards reinvented by Dr. Wollaston), and expended time, money, and ingenuity to no inconsiderable amount, in attempting to perfect the marine top for producing a true horizontal reflecting surface at sea. The marine barometer, the snuff-box sextant, and the portable universal dial, owe to him all their elegance, and much of their accuracy. Where others invented or sketched, he perfected.
In the ordinary physical apparatus, he made considerable improvement in the construction of the balance, and of the mountain barometer. In the same class may be mentioned, the form given to the compensated mercurial pendulum; his pyrometer, by which some very valuable expansions have been determined; the apparatus by which Sir George Shuckburgh attempted to ascertain the standard of weight and measure; and that which, in the hands of Mr. Baily, has given an invariable simple seconds pendulum. On the length of the simple pendulum Mr. Troughton himself made many very careful and extensive experiments, according to views and after a procedure of his own; but his ideas, though ingenious and elegant, were not pursued after Captain Kater's happy application of Huyghen's theorem. The apparatus for determining the Standard Scale of this Society is noticed in the present Report, and described in Mr. Baily's memoir. In the ordinary geodesical instruments Mr. Troughton greatly improved the surveying level and staff, and reduced them both in weight and price with increased convenience and accuracy. The errors of the common surveying chain, which are sometimes enormous, and the complexity and expense of that made by Ramsden for the trigonometrical survey, led to the construction of a more simple and accurate chain, at a reasonable cost and of easy use. The larger theodolites by Mr. Troughton, those for instance of twelve inches diameter, are remarkable for simplicity and power. In the refined and delicate instruments which have been applied to the most accurate geodesical measurements, we may mention the large theodolite for the American coast survey (1815), and those for the Irish (1822) and for the Indian surveys (1830), which may be advantageously contrasted, for their design and simplicity, with those, however otherwise excellent, of Ramsden; and also the apparatus for measuring a base line (1827), employed by Colonel Colby in Ireland, and Colonel Everest in India (1829). It must not, however, be forgotten, that the idea of this last most exquisite apparatus, and very much of the novelty of the construction, are due to our excellent members, Colonel Colby and Lieutenant Drummond. Mr. Troughton made some very beautiful and manageable zenith sectors, which were capable of great accuracy, considering their dimensions: one of these is, we believe, in the possession of the Danish government, and was employed in the Holstein survey by Professors Schumacher and Gauss. He had designed one for America on the same construction, with a six-feet telescope and arc, but it was never completed, though considerable progress had been made.
It is, however, more properly with the astronomical instruments of this great artist that we are immediately concerned; and here he reigns without a rival. His portable astronomical quadrants are models of strength and lightness. In the small altitude and azimuth circle (1792), the portable transit, and the portable universal equatorial, it is not easy to state accurately the line between his improvements or inventions, and those of preceding artists; but it is from him that these instruments received their present form and perfection. The repeating circle of Borda, an instrument which he disliked, first received its beauty and accuracy from his hands; and for it he invented his very elegant double-foot screw, to give minute adjustments. The ordinary reading micrometer, and the position micrometer commonly employed in the measurement of double stars, were greatly improved by him in simplicity and brought to perfection; and he first applied the former to dividing, though in circles and scales it had already been used in the reading off. In the class of larger altitude circles, revolving freely in azimuth, we find the circle for Count Bruhl (1792), the Westbury circle (1806), that for Sir T. M. Brisbane, the Society's Lee circle, the substance and form of Dr. Pearson's circle, those employed in the Indian survey for determining latitudes (1830), and that at the Edinburgh observatory (1830), with many others which it would be tedious to mention. In Groombridge's transit circle (1806), the beauty of the form and accuracy of the divisions satisfied every body but the artist himself, whose experience and matured powers were finally exhibited in the mural circle. This finished specimen of sound engineering and mechanical construction at first met with much opposition; and many were the objections, both before and after the erection of the Greenwich mural (1812), with which its inventor was assailed. To these he resolutely turned a deaf ear, for nothing could shake his confidence in what he knew; and he had the pleasure of finding, before his death, the mural circle established not only at the Royal Observatory of Paris, but also at the Cape, St. Helena, Madras, Cracow (1832), Edinburgh (1834), Brussels (1835), Cadiz, Armagh, and Cambridge (1832). A small model, of two feet in diameter, was made for Sir T. M. Brisbane prior to the Greenwich mural, and is now at the observatory of Paramatta. The principal equatorial instruments of Mr. Troughton, with accurately divided circles, are those of Coimbra (1788), Armagh and Brussels (1834). When we add to this long catalogue the large transits at Greenwich (1816), Camden Hill (1820), Cracow (1828), Markrea (1832), &c., in which the differential screws are so beautifully applied to form what he called the bones of the instrument, and the gigantic zenith tube at Greenwich, which he just finished before his strength failed, we have reason to wonder that even his long and active life should have sufficed for works of such variety and extent, and may form some estimate of the value of Mr. Troughton's labours, and their effect on modern astronomy. It may, perhaps, be remarked, that the only astronomical instrument which is not greatly indebted to Mr. Troughton is the telescope; and he was deterred from any attempt in this branch of his art, by a singular physical defect, which existed in many members of his family. He could not distinguish colours, and had little idea of them, except generally as they conveyed the idea of greater or less light. The ripe cherry and its leaf were to him of one hue, only to be distinguished by their form; and he was in the habit of relating some curious mistakes committed by himself, and others of his relations, in confounding green and red. With this defect in his vision, he never attempted any experiments in which colour was concerned; and it is difficult to see how he could have done so with success.
The most remarkable of Mr. Troughton's writings are, "An account of a method of dividing astronomical and other instruments by ocular inspection," &c., printed in the Phil. Trans. 1809, which was rewarded with the Copley medal; "A comparison of the repeating circle of Borda with the altitude and azimuth circle," in the Ist volume of this Society's Memoirs; and several articles in Brewster's Edinburgh Encyclopædia, such as "Circle," "Graduation," &c. The descriptions of instruments of his invention or construction, may generally be considered to have been furnished by him to the authors of the articles in which they appear; and an experienced judge will easily distinguish by the peculiar conciseness of his style (for he wrote in the same spirit as he constructed), the cases, and also the extent, to which this remark applies. His method of dividing has been generally adopted, and with the obvious modification of dividing by diameters instead of radii, so as to eliminate any defect in the turning of the collar or rim, has not received, and seems scarcely to require, any further improvement. In 1825, Mr. Troughton paid a visit to Paris, where he was received with great cordiality and respect by the distinguished artists and men of science of that metropolis. In 1830, he received an honorary gold medal from his majesty the King of Denmark.
Mr. Troughton was one of the original members of this Society, and at all times sincerely anxious for its prosperity. So long as his health permitted, he continued to be a constant attendant, notwithstanding his deafness, on the meetings of the council, and the ordinary meetings of the Society; and his valuable assistance and advice were most readily afforded whenever they were required. His singularly clear understanding, his unimpeachable integrity, and kind, though independent temper, made him universally respected; and there was an originality and raciness in his conversation and anecdotes rarely to be met with. At times, his criticisms might be considered to be severe, but never unfair, except, perhaps, on his ancient antagonist Ramsden, against whom he fancied he had grounds for complaint. In every other instance he was as ready to praise as to censure, and gave full and hearty approbation to the masterly conceptions of Graham, the beautiful execution of Bird, and the ingenuity and fertile invention of Ramsden himself. Nor was he niggardly towards his contemporaries and juniors. It may be added, that notwithstanding his high reputation and very simple habits, his carelessness of money did not allow him to become rich, for his object was fame rather than wealth. The following are references to the books in which Troughton's principal instruments are described :-
British Reflecting Circle. Brewster's Encyclopædia, vol. vi. p. 488. Plates CXLIV. V.
Nautical Top. Brewster's Encyclopædia, vol. xviii. p. 70. Sir G. E. Shuckburgh's Scale and Apparatus. Phil. Trans. 1798, p. 133, Plates v. VI . VIL.
Mr. Baily's Pendulum. Phil. Trans. 1832, p. 403.
Astronomical Society's Scale, &c. Mr. Baily's Report, &c. Mem. Royal Ast. Soc. vol. ix.
Portable Zenith Sector. Pearson's Pract. Astron., vol. ii. p. 546. Plate XXXII.
Astronomical Quadrant. Brewster's Encyclopædia, vol. ii. p. 725. Plate XLV.
Astronomical Quadrant. Pearson's Pract. Astron., vol. ii. p. 555. Plate XXIX.
Portable Altitude and Azimuth. Brewster's Encyclopædia, vol. vi. p. 492. Plate CXLVI.
Borda's Repeating Circle. Brewster's Encyclop., vol. vi. p. 498. Plate CXLVII.
For these two instruments, see Mr. Troughton's Memoir in the 1st volume of the Astronomical Society's Memoirs.
Position Micrometer. Pearson's Pract. Ast., vol. ii. p. 99. Plate x1. figs. 1, 2, 3.
Westbury Circle. Pisil. Trans. 1006, p. 420. Plate xx.
Sir T. M. Brisbane's Circle. Brewster's Encyclop., vol. ii. p. 727. Plate XLVI.
Pearson's Circle. Pearson's Practical Astronomy, vol. ii. p. 434. Plate XIX.
This circle was divided by Mr. Thomas Jones by Mr. Troughton's method. Groombridge's Transit Circle. Pearson's Practical Astronomy, vol. ii. p. 402. Plate XVII.
Mural Circle. Plate in Pond's Observations, vol. i.; Pearson's Practical As. tronomy, vol. ii. p. 472, Plate xx., but no detailed description of the instru-ment has yet appeared. The circles of Edinburgh, Brussels, Cracow, and Cambridge, are by Messrs. Troughton and Simms.
Coimbra Equatorial. Pearson's Pract. Astronomy, vol. ii. p. 519. Plate xxv.
Armagh Equatorial. Rees' Cyc., vol. xiii. Art. "Equatorial;" Plate XVI., Astron. Instr. Transact. Royal Irish Academy, vol. xv. p. 1.
Greenwich Transit. Pearson's Pract. Astronomy, vol. ii. p. 366. Plate XVI.
Camden Hill Transit. Phil. Trans. 1826, p. 423. Plates XVI., XVII.
Edward Troughton's obituary appeared in Journal of the Royal Astronomical Society 3:2 (1836), 149-155.