MacTutor
ROBERT STAWELL BALL was born in Dublin on July 1, 1840. He was the eldest of the three sons of Dr. Robert Ball, a well-known naturalist. The three brothers all became distinguished in science the eldest as Lowndean Professor of Astronomy at Cambridge; the second, Dr. Valentine Ball, as Director of the Science and Art Museum in Dublin; and the youngest, Sir Charles Ball, as an eminent surgeon.
Robert Stawell Ball received his earliest education at a preparatory school in Dublin, proceeding in 1851 to Dr. Brindley's school at Tarvin near Chester, where he first began the study of mathematics to which he devoted so much of his later career. In 1857 he entered Trinity College, Dublin, and soon showed his aptitude for mathematics. In 1860 he obtained a scholarship at the Lloyd Exhibition. In 1861 he was Gold Medalist in Mathematics, the first Gold Medalist in Experimental and Natural Science, and a university student.
It is stated that while at school Ball's interest in astronomy was awakened by reading Mitchell's Orbs of Heaven, which had just been published. At this time there were hardly any books which presented astronomy in a popular form, and Mitchell's books were widely read This may have had some influence on Ball's mind in after years, in trying to awaken others to the interest of astronomy through his many popular books and lectures. At college Ball studied the class-book on the Elements of Plane Astronomy which Brinkley had prepared for Dublin University. He also studied the Principia and Laplace. Thus prepared, he attracted the attention of Dr. Johnstone Stoney, who, in 1865, recommended him to Lord Rosse as assistant astronomer, and tutor to his sons. He worked with the 6-foot reflector at Parsonstown, chiefly in observations and micrometric measurements of faint nebulae. It is pointed out by Dr. Dreyer stated that "Ball was the first observer to use that telescope to correct the position angles for the error due to the instrument not being equatorially mounted, but supported at its lower end by a universal joint, the fixed axis of which was horizontal, in the east and west direction. This procedure, which materially improved the observations, was a natural outcome of Ball's geometrical instincts." In 1867 Ball quit Lord Rosse's observatory on his appointment to the professorship of Applied Mathematics in the newly founded Royal College of Science in Dublin. It was while in this position that he first began to give popular lectures on science.
In 1874, Brünnow, on account of failing health and eyesight, resigned his position as Andrews Professor of Astronomy and Royal Astronomer for Ireland, and Ball was appointed in his place. The Dunsink Observatory had been reorganized by Brünnow, who had mounted the 11-inch object glass presented by Sir James South, to form an excellent equatorial for the research on stellar parallax, to which he devoted himself. His predecessor, Brinkley, had undertaken the same line of research. Ball determined to continue the difficult investigations thus initiated, and it was at Dunsink that he produced his most important contributions to astronomy. Some delay occurred in effecting improvements to the equatorial, and it was not until 1876 that Ball commenced his work on stellar parallax. He selected the star 61 Cygni, on which he made a long series of observations of the difference in declination between the preceding component of 61 Cygni and a following small star of the ninth or tenth magnitude. Only after the observations were begun did he find that Brünnow, whose investigation of the same star he had intended to follow, had observed the following component of 61 Cygni, as had been done by Struve (with, however, a different comparison star). He decided to continue, and in 1877 he finally determined the parallax to be +0''.4654 ±0''.497. In 1878 he began a new investigation of the difference in declination between the following component of 61 Cygni and the same small star as had been used by Brünnow, so that this series would form a continuation to that of his predecessor. The final result for the parallax was +0''.4676 ±0''.0321. Struve had obtained, from the mean of two methods, a parallax of 0''.505, and Bessel, as rediscussed by C. A. F. Peters, 0''.360. Ball remarks that the agreement between his two series is so close that it is clearly due to some extent to the chapter on accidents, and he adds, "It would, however, seem that these investigations render it probable that the annual parallax of 61 Cygni is nearer the half-second found by Struve than the third of a second found by Bessel."
In 1876, Ball commenced a systematic search for stars with a large annual parallax, which occupied him for the succeeding five years. In selecting the stars for investigation, he adopted the views which had been expressed by Schiaparelli in one direction and by Johnstone Stoney in another Schiaparelli had remarked that it is possible that the stars which are really nearest to us belong, in some sort, to the same system as our Sun, are therefore animated by somewhat the same motion in space, and consequently do not exhibit the phenomenon of proper motion to a remarkable degree. In a communication to the Royal Society Johnstone Stoney says: "The minute crimson stars which are met with here and there in the sky seem to be either very small stars, or stars enormously distended by heat. It is very desirable that the proper motion and parallax of these bodies should be inquired into, on the chance that some of them may be found to owe their colour to being very small and therefore very close to us." Accordingly, Ball selected for his inquiry stars with small proper motion, and others which were red stars. His observations are contained in two memoirs published in Parts III and V of the Dunsink Observations. The first series gives the investigation of 42 stars, and the second of 367 stars: every observation was made by Ball himself. The practical conclusion he thus announces: "In the great majority of cases the results pronounce emphatically against the supposition of a parallax large enough to be detected amid the errors of observation inseparable from the method adopted. In no case do they afford reliable indications of a parallax large enough to be detected by the method of reconnoitring." Besides 61 Cygni, Ball made determinations of the parallax of Groombridge 1618, π = +0''.322 ± 0''.023, and of 6 Cygni, +0''.482 ±0''.054. He also essayed a determination of the parallax of Piazzi III. 242, but the result was negative.
Sir Robert Ball's fame in the history of science will rest more on his eminent power as a mathematician than on his contributions to astronomy.
The origin of his great work, The Theory of Screws, may be best given in his own words He says: "In the spring of 1869 I happened to attend a lecture at the Royal Dublin Society, given by my friend Dr. G. Johnstone Stoney. For one illustration he used a conical pendulum to exhibit and explain the progression of the apse in the ellipse described by a heavy ball suspended from a long wire. I was much interested by his exposition and immediately began to work on the mathematical theory of the subject, in the endeavour to understand it more fully. I was thus led to investigate some general problems relating to the small oscillations of a particle on a surface. Certain results, at which I arrived, seemed to me interesting and novel. They appeared as a paper in the Quarterly Journal of Pure and Applied Mathematics, 1869, under the title 'A Problem in Mechanics'. This paper was soon followed by another on "The Small Oscillations of a Rigid Body about a Fixed Point under the Action of any Forces, and more particularly when Gravity is the only Force acting." (Transactions of the Royal Irish Academy, vol. xxiv.) The subject then began to develop into what I ventured to call The Theory of Screws. The first memoir with this title appeared in 1872; the twelfth and last in 1897. Ball, however, published three additional memoirs: "Further Developments of the Geometrical Theory of Screws" (1901); "On the Reflection of Screw Systems and Allied Questions" (1902); and "Some Extensions of the Theory of Screws" (1903, 4).
Only brief reference can be made to this important work in the present notice, and the following account is taken from the fuller description of the Theory of Screws in the Proceedings of the Royal Society, vol. cxi. (Obituaries, p. xx):-
"Ball's Theory of Screws gives a very complete geometrical treatment of the problems of small movements in rigid dynamics, and in that respect is unique among English books. The small first edition appeared in 1876, and the large and comprehensive volume was published by the Cambridge University Press in 1900.
"The keynote to the whole method consists in the use of the 'screw,' consisting of a line in space together with an associated length or 'pitch.' This geometrical entity has a double use, representing either the most general system of forces or the most general kind of small displacement. In the former case, it gives the axis and pitch of a wrench, in the latter of a 'twist.' For either physical interpretation, the geometrical development is the same. Interesting derivative relationships between screws can be followed. For example, reciprocal screws, when a wrench along one does no work for a twist along the other; and conjugate screws, when a wrench along one produces instantaneous twist along the other. Notable use is made throughout the work of the 'cylindroid' surface, which appears in statics as the surface traced out by the resultant of two wrenches of varying intensities along given screws. Ball was not the actual discoverer of the cylindroid (Hamilton and Plucker had found its chief property earlier), but he certainly counts as its chief patron. He always took a lively interest in any development of its properties, and a beautifully made model placed in the collection of Cambridge University serves as a memento of its former owner."
"For a most admirable and appreciative survey of the scope of Ball's work on screws, reference may be made to a review by Henrici (Nature, 1890) of the treatise Theoretische Mechanik Rigrer Systeme by Gravelius, which is founded mainly upon Ball's memoirs. An excellent account was given by Ball himself in his presidential address to the Mathematical Section of the British Association in 1887. He uses some geometrical abstractions, quaintly personified, as speakers in a discussion; and, under this whimsical garb, reveals the essence of his methods very pertinently and clearly. Throughout all of Ball's work, there is a fine enthusiasm for his subject and a most generous appreciation of the discoveries of others. In 1879, the Royal Irish Academy awarded him the Cunningham Gold Medal, and his name thus appears in a list which also includes those of Casey, MacCullagh, Hamilton, Jellett, and Salmon. By his many and excellent contributions to geometry of kinematics and dynamics, Robert Stawell Ball assuredly takes an honorable place on the roll of Irish mathematicians.
Among Ball's contributions to the Monthly Notices may be mentioned: "On a Simple Approximate Method of Calculating the Effect of Refraction upon the Distance and Position-Angle of Two Adjacent Stars"; "On a Transformation of Lagrange's Equations of Motion into Generalized Coordinates"; "On the Single Equation which comprises the Theory of the Fundamental Instruments of the Observatory"; "Micrometric Observations of Nova Andromedæ"; and "On the Orbit of the Binary Star & Urssæ Majoris."
Through his numerous books and lectures, Sir Robert Ball is conspicuously identified as the most popular expositor of astronomy this country has ever possessed. His popular books The Story of the Heavens, Starland, In the High Heavens, Time and Tide, The Cause of an Ice Age, The Story of the Sun, Great Astronomers, and others are all written in a clear and attractive style and have been widely read. In 1880, he published an excellent textbook on the Elements of Astronomy, and in 1908, he issued a very useful Treatise on Spherical Astronomy for the use of Cambridge University students.
For more than 30 years, Sir Robert Ball has been renowned for the popular lectures he delivered throughout this country, and in many places in Canada and the United States. An important research advances astronomy in a specific direction, but it is a question whether the science in general may not be advanced
Ultimately, to a greater degree, by the presentation of astronomical facts and astronomical research in lucid and attractive lectures to large numbers of people, who would be encouraged, stimulated, and guided to more advanced study. In an admirable discourse on lecturing, delivered by Mr. Goschen over thirty years ago, he said: "The lecture has a great advantage over reading in its educational influence, inasmuch as it gives the lecturer a power of exciting interest and enthusiasm for his subject through his inspiring personality. The voice and manner of the lecturer will do more than any tricks of style can do. A book may excite interest and enthusiasm, but personal contact is much more likely to do it. Writing that inspires is rarer than inspiring speech, and lecturers have not fulfilled their function unless they inspire the interest and enthusiasm of their hearers. Lecturers, if they are suggestive, are not only signposts pointing towards the direction in which you ought to go, but they see you safely started on your journey and take you to wider fields of literature and wider fields of thought." These were the attributes of a lecturer that Ball possessed to an eminent degree. The great popularity that he achieved is convincing evidence of the broad interest in astronomy that he thus aroused. It is common knowledge how small the influence that affects a receptive mind may be and leads to further study and development, and in this way Ball's lectures have given a strong impetus to the advancement of the study of astronomy in this country.
On the death of Professor J. C. Adams at the beginning of 1892, Sir Robert Ball was elected to succeed him as Lowndean Professor of Astronomy and Geometry, and also as Director of the University Observatory at Cambridge; positions which he held up to the time of his death. Soon after, he was elected a Fellow of King's College, Cambridge. He was an honorary M.A. from Cambridge, and an LL.D. from Dublin. It is recorded that as a lecturer on the mathematical side of astronomy, Ball showed the same lucid qualities which made him so effective in a more popular sphere. He gave the young student an insight into the methods of the classical writers in celestial mechanics and prepared the way for the study of later advances.
In 1884, Ball became Scientific Adviser to the Commission of Irish Lights, in succession to Tyndall, and he always took the greatest delight in the annual cruise of the Commissioners around Ireland to inspect the lighthouses. On January 25, 1886, he received the honour of knighthood from the Lord Lieutenant of Ireland. He was elected a Fellow of the Royal Society in 1873 and served on the Council in 1897-98. He was President of the Royal Astronomical Society from 1897 to 1899 and for ten years was a member of the Council.
Sir Robert Ball had a charming personality. His kindly and sympathetic nature, his full appreciation of the labours of others, and his keen sense of humour made him greatly beloved and respected by all his friends. For the last two years of his life he was seriously ill, but happily without suffering, and he died at Cambridge on November 25, 1913, and was buried in St. Giles Churchyard, where also lie the remains of his illustrious predecessor. In 1868 he married the daughter of Dr. W. E. Steele, Director of the Science and Art Museum in Dublin, who survives him with his four sons and two daughters.
He was elected a Fellow of this Society on March 12, 1875.
E. B. K
Robert Stawell Ball received his earliest education at a preparatory school in Dublin, proceeding in 1851 to Dr. Brindley's school at Tarvin near Chester, where he first began the study of mathematics to which he devoted so much of his later career. In 1857 he entered Trinity College, Dublin, and soon showed his aptitude for mathematics. In 1860 he obtained a scholarship at the Lloyd Exhibition. In 1861 he was Gold Medalist in Mathematics, the first Gold Medalist in Experimental and Natural Science, and a university student.
It is stated that while at school Ball's interest in astronomy was awakened by reading Mitchell's Orbs of Heaven, which had just been published. At this time there were hardly any books which presented astronomy in a popular form, and Mitchell's books were widely read This may have had some influence on Ball's mind in after years, in trying to awaken others to the interest of astronomy through his many popular books and lectures. At college Ball studied the class-book on the Elements of Plane Astronomy which Brinkley had prepared for Dublin University. He also studied the Principia and Laplace. Thus prepared, he attracted the attention of Dr. Johnstone Stoney, who, in 1865, recommended him to Lord Rosse as assistant astronomer, and tutor to his sons. He worked with the 6-foot reflector at Parsonstown, chiefly in observations and micrometric measurements of faint nebulae. It is pointed out by Dr. Dreyer stated that "Ball was the first observer to use that telescope to correct the position angles for the error due to the instrument not being equatorially mounted, but supported at its lower end by a universal joint, the fixed axis of which was horizontal, in the east and west direction. This procedure, which materially improved the observations, was a natural outcome of Ball's geometrical instincts." In 1867 Ball quit Lord Rosse's observatory on his appointment to the professorship of Applied Mathematics in the newly founded Royal College of Science in Dublin. It was while in this position that he first began to give popular lectures on science.
In 1874, Brünnow, on account of failing health and eyesight, resigned his position as Andrews Professor of Astronomy and Royal Astronomer for Ireland, and Ball was appointed in his place. The Dunsink Observatory had been reorganized by Brünnow, who had mounted the 11-inch object glass presented by Sir James South, to form an excellent equatorial for the research on stellar parallax, to which he devoted himself. His predecessor, Brinkley, had undertaken the same line of research. Ball determined to continue the difficult investigations thus initiated, and it was at Dunsink that he produced his most important contributions to astronomy. Some delay occurred in effecting improvements to the equatorial, and it was not until 1876 that Ball commenced his work on stellar parallax. He selected the star 61 Cygni, on which he made a long series of observations of the difference in declination between the preceding component of 61 Cygni and a following small star of the ninth or tenth magnitude. Only after the observations were begun did he find that Brünnow, whose investigation of the same star he had intended to follow, had observed the following component of 61 Cygni, as had been done by Struve (with, however, a different comparison star). He decided to continue, and in 1877 he finally determined the parallax to be +0''.4654 ±0''.497. In 1878 he began a new investigation of the difference in declination between the following component of 61 Cygni and the same small star as had been used by Brünnow, so that this series would form a continuation to that of his predecessor. The final result for the parallax was +0''.4676 ±0''.0321. Struve had obtained, from the mean of two methods, a parallax of 0''.505, and Bessel, as rediscussed by C. A. F. Peters, 0''.360. Ball remarks that the agreement between his two series is so close that it is clearly due to some extent to the chapter on accidents, and he adds, "It would, however, seem that these investigations render it probable that the annual parallax of 61 Cygni is nearer the half-second found by Struve than the third of a second found by Bessel."
In 1876, Ball commenced a systematic search for stars with a large annual parallax, which occupied him for the succeeding five years. In selecting the stars for investigation, he adopted the views which had been expressed by Schiaparelli in one direction and by Johnstone Stoney in another Schiaparelli had remarked that it is possible that the stars which are really nearest to us belong, in some sort, to the same system as our Sun, are therefore animated by somewhat the same motion in space, and consequently do not exhibit the phenomenon of proper motion to a remarkable degree. In a communication to the Royal Society Johnstone Stoney says: "The minute crimson stars which are met with here and there in the sky seem to be either very small stars, or stars enormously distended by heat. It is very desirable that the proper motion and parallax of these bodies should be inquired into, on the chance that some of them may be found to owe their colour to being very small and therefore very close to us." Accordingly, Ball selected for his inquiry stars with small proper motion, and others which were red stars. His observations are contained in two memoirs published in Parts III and V of the Dunsink Observations. The first series gives the investigation of 42 stars, and the second of 367 stars: every observation was made by Ball himself. The practical conclusion he thus announces: "In the great majority of cases the results pronounce emphatically against the supposition of a parallax large enough to be detected amid the errors of observation inseparable from the method adopted. In no case do they afford reliable indications of a parallax large enough to be detected by the method of reconnoitring." Besides 61 Cygni, Ball made determinations of the parallax of Groombridge 1618, π = +0''.322 ± 0''.023, and of 6 Cygni, +0''.482 ±0''.054. He also essayed a determination of the parallax of Piazzi III. 242, but the result was negative.
Sir Robert Ball's fame in the history of science will rest more on his eminent power as a mathematician than on his contributions to astronomy.
The origin of his great work, The Theory of Screws, may be best given in his own words He says: "In the spring of 1869 I happened to attend a lecture at the Royal Dublin Society, given by my friend Dr. G. Johnstone Stoney. For one illustration he used a conical pendulum to exhibit and explain the progression of the apse in the ellipse described by a heavy ball suspended from a long wire. I was much interested by his exposition and immediately began to work on the mathematical theory of the subject, in the endeavour to understand it more fully. I was thus led to investigate some general problems relating to the small oscillations of a particle on a surface. Certain results, at which I arrived, seemed to me interesting and novel. They appeared as a paper in the Quarterly Journal of Pure and Applied Mathematics, 1869, under the title 'A Problem in Mechanics'. This paper was soon followed by another on "The Small Oscillations of a Rigid Body about a Fixed Point under the Action of any Forces, and more particularly when Gravity is the only Force acting." (Transactions of the Royal Irish Academy, vol. xxiv.) The subject then began to develop into what I ventured to call The Theory of Screws. The first memoir with this title appeared in 1872; the twelfth and last in 1897. Ball, however, published three additional memoirs: "Further Developments of the Geometrical Theory of Screws" (1901); "On the Reflection of Screw Systems and Allied Questions" (1902); and "Some Extensions of the Theory of Screws" (1903, 4).
Only brief reference can be made to this important work in the present notice, and the following account is taken from the fuller description of the Theory of Screws in the Proceedings of the Royal Society, vol. cxi. (Obituaries, p. xx):-
"Ball's Theory of Screws gives a very complete geometrical treatment of the problems of small movements in rigid dynamics, and in that respect is unique among English books. The small first edition appeared in 1876, and the large and comprehensive volume was published by the Cambridge University Press in 1900.
"The keynote to the whole method consists in the use of the 'screw,' consisting of a line in space together with an associated length or 'pitch.' This geometrical entity has a double use, representing either the most general system of forces or the most general kind of small displacement. In the former case, it gives the axis and pitch of a wrench, in the latter of a 'twist.' For either physical interpretation, the geometrical development is the same. Interesting derivative relationships between screws can be followed. For example, reciprocal screws, when a wrench along one does no work for a twist along the other; and conjugate screws, when a wrench along one produces instantaneous twist along the other. Notable use is made throughout the work of the 'cylindroid' surface, which appears in statics as the surface traced out by the resultant of two wrenches of varying intensities along given screws. Ball was not the actual discoverer of the cylindroid (Hamilton and Plucker had found its chief property earlier), but he certainly counts as its chief patron. He always took a lively interest in any development of its properties, and a beautifully made model placed in the collection of Cambridge University serves as a memento of its former owner."
"For a most admirable and appreciative survey of the scope of Ball's work on screws, reference may be made to a review by Henrici (Nature, 1890) of the treatise Theoretische Mechanik Rigrer Systeme by Gravelius, which is founded mainly upon Ball's memoirs. An excellent account was given by Ball himself in his presidential address to the Mathematical Section of the British Association in 1887. He uses some geometrical abstractions, quaintly personified, as speakers in a discussion; and, under this whimsical garb, reveals the essence of his methods very pertinently and clearly. Throughout all of Ball's work, there is a fine enthusiasm for his subject and a most generous appreciation of the discoveries of others. In 1879, the Royal Irish Academy awarded him the Cunningham Gold Medal, and his name thus appears in a list which also includes those of Casey, MacCullagh, Hamilton, Jellett, and Salmon. By his many and excellent contributions to geometry of kinematics and dynamics, Robert Stawell Ball assuredly takes an honorable place on the roll of Irish mathematicians.
Among Ball's contributions to the Monthly Notices may be mentioned: "On a Simple Approximate Method of Calculating the Effect of Refraction upon the Distance and Position-Angle of Two Adjacent Stars"; "On a Transformation of Lagrange's Equations of Motion into Generalized Coordinates"; "On the Single Equation which comprises the Theory of the Fundamental Instruments of the Observatory"; "Micrometric Observations of Nova Andromedæ"; and "On the Orbit of the Binary Star & Urssæ Majoris."
Through his numerous books and lectures, Sir Robert Ball is conspicuously identified as the most popular expositor of astronomy this country has ever possessed. His popular books The Story of the Heavens, Starland, In the High Heavens, Time and Tide, The Cause of an Ice Age, The Story of the Sun, Great Astronomers, and others are all written in a clear and attractive style and have been widely read. In 1880, he published an excellent textbook on the Elements of Astronomy, and in 1908, he issued a very useful Treatise on Spherical Astronomy for the use of Cambridge University students.
For more than 30 years, Sir Robert Ball has been renowned for the popular lectures he delivered throughout this country, and in many places in Canada and the United States. An important research advances astronomy in a specific direction, but it is a question whether the science in general may not be advanced
Ultimately, to a greater degree, by the presentation of astronomical facts and astronomical research in lucid and attractive lectures to large numbers of people, who would be encouraged, stimulated, and guided to more advanced study. In an admirable discourse on lecturing, delivered by Mr. Goschen over thirty years ago, he said: "The lecture has a great advantage over reading in its educational influence, inasmuch as it gives the lecturer a power of exciting interest and enthusiasm for his subject through his inspiring personality. The voice and manner of the lecturer will do more than any tricks of style can do. A book may excite interest and enthusiasm, but personal contact is much more likely to do it. Writing that inspires is rarer than inspiring speech, and lecturers have not fulfilled their function unless they inspire the interest and enthusiasm of their hearers. Lecturers, if they are suggestive, are not only signposts pointing towards the direction in which you ought to go, but they see you safely started on your journey and take you to wider fields of literature and wider fields of thought." These were the attributes of a lecturer that Ball possessed to an eminent degree. The great popularity that he achieved is convincing evidence of the broad interest in astronomy that he thus aroused. It is common knowledge how small the influence that affects a receptive mind may be and leads to further study and development, and in this way Ball's lectures have given a strong impetus to the advancement of the study of astronomy in this country.
On the death of Professor J. C. Adams at the beginning of 1892, Sir Robert Ball was elected to succeed him as Lowndean Professor of Astronomy and Geometry, and also as Director of the University Observatory at Cambridge; positions which he held up to the time of his death. Soon after, he was elected a Fellow of King's College, Cambridge. He was an honorary M.A. from Cambridge, and an LL.D. from Dublin. It is recorded that as a lecturer on the mathematical side of astronomy, Ball showed the same lucid qualities which made him so effective in a more popular sphere. He gave the young student an insight into the methods of the classical writers in celestial mechanics and prepared the way for the study of later advances.
In 1884, Ball became Scientific Adviser to the Commission of Irish Lights, in succession to Tyndall, and he always took the greatest delight in the annual cruise of the Commissioners around Ireland to inspect the lighthouses. On January 25, 1886, he received the honour of knighthood from the Lord Lieutenant of Ireland. He was elected a Fellow of the Royal Society in 1873 and served on the Council in 1897-98. He was President of the Royal Astronomical Society from 1897 to 1899 and for ten years was a member of the Council.
Sir Robert Ball had a charming personality. His kindly and sympathetic nature, his full appreciation of the labours of others, and his keen sense of humour made him greatly beloved and respected by all his friends. For the last two years of his life he was seriously ill, but happily without suffering, and he died at Cambridge on November 25, 1913, and was buried in St. Giles Churchyard, where also lie the remains of his illustrious predecessor. In 1868 he married the daughter of Dr. W. E. Steele, Director of the Science and Art Museum in Dublin, who survives him with his four sons and two daughters.
He was elected a Fellow of this Society on March 12, 1875.
E. B. K
Robert Stawell Ball's obituary appeared in Journal of the Royal Astronomical Society 75:4 (1915), 230-236.