# Lectures on Ten British Physicists of the Nineteenth Century/Lecture 10

SIR JOHN FREDERICK WILLIAM HERSCHEL
(1792-1871)
John Frederick William Herschel was born on the 7th of March, 1792, at the village of Slough, near Windsor, England. His father was Sir William Herschel, a native of Hanover, Germany, who migrated in his youth to England, became an organist and choir master at Bath, at the same time as an amateur astronomer constructed powerful reflecting telescopes by means of which he discovered a new planet Uranus, and was invited by George III to become astronomer to the court at Windsor. He finally established himself in the village of Slough, in a house where there was a suitable grassplot for the erection of his celebrated large reflecting telescope. The mother of John Herschel, née Mary Baldwin, was the only daughter of a London merchant, had been a widow, and had brought to his father a moderate fortune. His father's salary as court astronomer was only £200, but he made much money from the construction of telescopes. John was their only child, and was thus the heir to considerable wealth. He received his primary education at a private school at Hitcham, Buckinghamshire, and was then sent to the great public school Eton in the neighborhood of Windsor; he remained there for a few months only, but when his mother saw him maltreated by a strange boy he was taken home and placed under the care of Mr. Rogers, a Scottish mathematician. He must have studied the classics thoroughly for at an advanced age he translated the whole of the Iliad into English hexameters. His father realized the importance of training in mathematics. At that time mathematical science had declined in England, through adulation of Newton and antipathy towards Leibnitz, but still flour​ished in Scotland. Herschel himself says, "In Scotland the torch of abstract science had never burnt so feebly nor decayed so far as in England; nor was a high priest of the sublimer muse ever wanting in those ancient shrines, where Gregory and Napier had paid homage to her power." At that time, a Scotsman named Ivory was almost the sole British mathematician who was in touch with the great mathematical progress being made on the Continent, especially in France. John Herschel possessed the great advantage of living in a home where the chief languages of the Continent were understood, and in which relations with abroad were still maintained.
At the age of 17 Herschel entered St. John's College, Cambridge. His principal undergraduate friends were Charles Babbage and George Peacock, and all three were impressed with the decline of mathematical science in England. Herschel thus describes the situation: "Students at our universities, fettered by no prejudices, entangled by no habits, and excited by the ardour and emulation of youth, had heard of the existence of masses of knowledge from which they were debarred by the mere accident of position. There required no more. No prestige which magnifies what is unknown, and the attraction inherent in what is forbidden, coincided in their impulse. The books were procured and read, and produced their natural effects. The brows of many a Cambridge moderator were elevated, half in ire, and half in admiration, at the unusual answers which began to appear in examination papers. Even moderators are not made of impenetrable stuff; their souls were touched, though fenced with sevenfold Jacquier, and tough bullhide of Vince and Wood. They were carried away with the stream, in short, or replaced by successors full of their newly-acquired powers. The modern analysis was adopted in its largest extent." The three undergraduates accomplished their object by forming an Analytical Society. The Society published a volume of memoirs but more important still they translated and published Lacroix's smaller Treatise on the Differential Calculus, to which Herschel added an appendix on Finite Differences.
​While undergraduates both Babbage and Herschel attended the lectures of the professor of Chemistry, they helped the professor to prepare his experiments, and they set up private laboratories for themselves. Herschel finished his undergraduate career in 1813 by being a senior wrangler; he also won the first Smith's prize. He was immediately elected to a fellowship in his college. While an undergraduate he wrote a paper on "A remarkable application of Cotes' Theorem," which was published in the Transactions of the Royal Society, and he had no sooner graduated than he was elected a Fellow of that Society. It was his father's desire that he should enter the church, but he himself preferred the profession of the law; so in 1814 he was entered as a student of Lincoln's Inn, London. Residence in the metropolis brought him into intimate relations with the principal scientists of the day; among whom was Wollaston, the physicist (who was the first to notice two or three of the most conspicuous dark lines of the solar spectrum) and South, the astronomer. By Wollaston he was influenced to take up chemistry and optics, and by South to turn his attention to the unfinished researches of his father. The professor of chemistry at Cambridge whom he had assisted was killed accidentally; Herschel applied for the chair, but unsuccessfully. After two years spent in London he returned to Slough with the definite purpose of taking up astronomical research. To this step lines written by himself doubtless refer:
During the six following years he worked at pure mathematics, astronomy, experimental optics and chemistry. It was in these years that he made his principal contributions to ​pure mathematics. Several of the papers which he contributed to the Royal Society dealt with the calculus of finite differences; for these he received the Copley medal in 1821. In astronomy, he revised the catalogue of double stars made by his father; this work he did in conjunction with (Sir James) South and with the help of two refracting telescopes the property of that scientist. The resulting catalogue, printed in the Philosophical Transactions, brought its author the gold medal of the recently instituted Astronomical Society of London; also the Lalande prize for astronomy (of the Paris Academy) for 1825. Herschel along with Babbage took an active part in the foundation of the Royal Astronomical Society; he wrote its inaugural address, and was its first foreign secretary, while his father was its first president. In optics he investigated the absorption of light by colored media and the action of crystals upon polarised light. In chemistry (1819, when philosophical chemistry was perhaps at its lowest ebb in England) he rediscovered the hyposulphite salts, and ascertained their leading properties, the principal of which is dissolving the nitrate of silver—a property applied by Daguerre twenty years later to fixing photographic pictures. In 1821 he traveled in Italy and Switzerland with Babbage.
In 1822 his father died. His mother continued to reside at Slough, and the younger Herschel now succeeded to all the property, astronomical and otherwise, of his father. His mother survived for ten years, and throughout this interval Herschel made his home at Slough, with the exception that for three years, 1824-7, while he was secretary of the Royal Society he had also a house in London. Towards the end of this interval he married, the object of his choice being Margaret Brodie Stewart, the daughter of a clergyman of the north of Scotland; in this as in many other matters Herschel was a fortunate man. In 1830 he was put forward as the scientific candidate for the presidency of the Royal Society, the titled candidate being the royal Duke of Sussex; in which contest rank prevailed, but the principle which Herschel stood for ultimately prevailed. In this interval he accomplished much work in astronomy. In ​1825 he received from his aunt, Caroline Herschel, a copy of her zone catalogue of nebulæ; in his reply he said, "Those curious objects I shall now take into my especial charge; nobody else can see them." He referred to his being the owner of a 20-foot "front view" reflector constructed by himself with his father's aid in 1820. With this instrument he made a great review of all the nebulæ visible in England, the result being a catalogue of 2307 nebulæ, of which 525 were discovered by himself; presented to the Royal Society in 1833. Herschel also continued the search for double stars, using the larger telescope which belonged to South; he discovered 3346 pairs, and made extensive measurements of known pairs.
For Lardner's Cabinet Cyclopedia he prepared an article on astronomy which was subsequently rewritten and published in 1849 as a book under the title Outlines of Astronomy. This book went through many editions, and was translated into many languages, even the Roman, Chinese and Arabic. For this Cyclopedia Herschel also prepared an introductory volume under the title Preliminary Discourse on the Study of Natural Philosophy. By Natural Philosophy he does not mean Physics only but it includes the experimental and observational sciences, namely, in the order of Herschel's book, Mechanics, Optics, Astronomy, Geology, Mineralogy, Chemistry, Heat, Electricity, Zoology, Botany. Herschel advanced several of these sciences, and had a special knowledge of all, excepting perhaps the two last; he was thus rarely well fitted to write on their logic and methods. The work treats of the methods of scientific research since the time of Francis Bacon. On the title page is a picture of Bacon and the words Naturæ minister et interpres taken from his first aphorism; (these words, as all in this audience know, are also in the motto of Lehigh University). In it will be found many of the philosophic ideas which were elaborated by the British mathematicians whose lives we have discussed. Here we find the idea, afterwards elaborated by Clerk Maxwell, that the atoms of the chemist bear the characters of "manufactured articles"; here we find the thought, elaborated by Tait in verse, that Nature presents to us in a confused and ​interwoven mass the elements of all our knowledge and that it is the business of the philosopher to disentangle, to arrange, and to present them in a separate and distinct state. In the works of these great scientists there is abundant evidence that this Discourse formed a guide arid inspiration, as indeed it did to all the British scientists of the nineteenth century. The Discourse was translated into French, German and Italian, and was reprinted in 1851.
After his mother's death Herschel prepared to carry out a long cherished project—a survey of the heavens in the southern hemisphere. The Government offered Mm a free passage in a ship-of-war; he preferred to pay his own way. On the 13th of November, 1833, he set sail with his family and instruments for the Cape of Good Hope, and arrived in the course of two months. He secured a house at Feldhausen, six miles from Cape Town, and there he erected his 20-foot reflector and 7-foot refractor, and applied them to the double stars and nebulae. He constructed a scale of brightness by fixing the relative brightness of nearly 500 stars, using for this purpose "the method of sequences." He made comparisons not only at the Cape, but on the voyage out and back. With an actinometer of his own invention he made the first satisfactory measures of direct solar radiation.
While Herschel was busy at the Cape, an article appeared day by day in the New York Sun pretending to give an account of some great astronomical discoveries he had made. It announced that he had discovered men, animals, etc., in the Moon, and gave much detail. The paper by this enterprise, increased its circulation five fold, and secured a permanent footing. The article printed separately had a large sale, and was translated into various languages. The author was R. A. Locke, the editor of the newspaper; but De Morgan thought it had been written by a professional astronomer.
While engaged with the stars, Herschel had also time to help the development of the educational system of the colony. He was instrumental in initiating an excellent system of national education. Consulted on the course of study for a South ​African College he gave his views in a letter which stated that too much time was given to the classical languages in the great English schools; that he attached great importance to all those branches of practical and theoretical knowledge whose possession goes to constitute an idea of a well-informed gentleman, namely, knowledge of the actual system and the laws of nature, both physical and moral; that in a free country it is important for every man to be trained in political economy and jurisprudence; that mathematics is the best training in reasoning, provided that it is supplemented with the inductive philosophy. He concluded, "Let your College have the glory—for glory it will be—to have given a new impulse to public instruction by placing the Novum Organum for the first time in the hands of young men educating for active life, as a textbook, and as a regular part of their College course."
After four years of work at the Cape Herschel returned to England, arriving in the middle of March, 1838. A great banquet was given him by his scientific contemporaries to which Hamilton came expressly from Dublin. Many honors came to Herschel; he had been knighted in 1831 and now he was made a baronet by Queen Victoria, on the occasion of her coronation (June, 1839); and from Oxford University, as one of the lions of the day he received the degree of D.C.L. In 1840 he removed his residence from Slough to the country house of Collingwood, near the village of Hawkhurst, in the County of Kent; and this remained almost without interruption the scene of his future labors. For eight years his principal work was the reduction of the results of his four years of observation at the Cape. From this retreat he was called forth one year to address the students of Marischel College, Aberdeen, as their lord rector. In the ancient universities the rector was the chosen head of the student body; in the Scottish Universities the office survives in an altered form. The rector is elected by the students, usually on political grounds, and his principal duty is to deliver an address at the beginning of his term of office. The leading politicians of the day were candidates for the honor. Occasionally as in the case of Herschel, ​Carlyle, Carnegie, the choice of the students is guided by other than political reasons. In 1843 Herschel made a reproduction of an engraving of the Slough 40-foot reflector which was the first example of a photograph on glass. He was the first person to use the terms positive and negative for photographic reproductions. His discovery in 1845 of the "epipolic" dispersion of light produced by sulphate of quinine and some other substances led the way to Stokes' explanation of the phenomena of fluorescence.
In 1845 Herschel was called on to preside at the second Cambridge meeting of the British Association. Since his own student days, Cambridge had made great progress in mathematical science. The "d-ists"' had long since triumphed over the dot-ards. The Cambridge Philosophical Society had been founded for the reading and publication of scientific memoirs; the Cambridge Mathematical Journal had been founded; and the University Observatory had been made an up-to-date institution. His immediate predecessor in the chair was another "d-ist", George Peacock, now dean of Ely; and after the close of the meeting Herschel and Hamilton were guests at the deanery, on which occasion both essayed their poetic power. Two years before the Quaternion theory had been published; and Herschel referred to it in his presidential address. The closing passage of this address is characteristic of the man: "In these our annual meetings, to which every corner of Britain —almost every nation in Europe—sends forth as its representative some distinguished cultivator of some separate branch of knowledge; where I would ask, in so vast a variety of pursuits which seem to have hardly anything in common, are we to look for that acknowledged source of delight which draws us together, and inspires us with a sense of unity? That astronomers should congregate to talk of stars and planets— chemists of atoms—geologists of strata—is natural enough; but what is there of equal mutual interest, equally connected with and equally pervading all they are engaged upon, which causes their hearts to burn within them for mutual communication and unbosoming? Surely, were each of us to give utterance ​to all he feels, we would hear the chemist, the astronomer, the physiologist, the electrician, the botanist, the geologist, all with one accord, and each in the language of his own science declaring not only the wonderful works of God disclosed by it, but the delight which their disclosure affords him, and the privilege he feels it to be to have aided in it. This is indeed a magnificent induction—a consilience there is no refusing. It leads us to look around, through the long vista of time, with chastened but confident assurance that science has still other and nobler work to do than any she has yet attempted; work which, before she is prepared to attempt, the minds of men must be prepared to receive the attempt; prepared, I mean, by an entire conviction of the wisdom of her views, the purity of her objects, and the faithfulness of her disciples."
In 1846 on resigning the chair at Southampton he announced that science was about to triumph in a remarkable way by predicting the position of a new planet. The following year, 1847, the Results of his observations at the Cape of Good Hope were published in one large quarto volume, the expense of publication being borne by the Duke of Northumberland; there may be found an extended catalogue of southern stars and nebulæ, with elaborate drawings and discussions of their relative and variable brightness. In 1850 the office of Master of the Mint, an office which had been held by Sir Isaac Newton, was changed from a political to a scientific appointment; and Herschel was appointed. He did not break up his home, but stayed himself in London as much as was necessary. He did not like the separation from his family, and after five years resigned. While holding this office, he also accepted a place on the Cambridge University Commission. After retiring from the Mint, he lived for sixteen years longer as the Sage of Collingwood. He was ever ready to help a younger or less fortunate man of science. He had an unbounded admiration for the genius and character of Sir W. R. Hamilton; he gave him practical counsel in the preparation of the "Elements of Quaternions," and in an indirect way assisted him financially in the education of his eldest son—a very unworthy recipient as events ​turned out. We have seen how he was the first to recognize the work of Adams; it is not wonderful then that he retained his great popularity to the last.
Herschel and his mathematical friends all advocated strenuously the decimalisation of the coinage; that is, to retain the pound as the standard fundamental unit of financial value, and to retain or adopt only such sub-units as were decimal parts of it; the florin is the tenth part, and the farthing nearly the 1000th part (very approximate 1/2 cent). Others advocated the shilling for the fundamental unit (=quarter dollar); the latter were called Little-endians, the former Big-endians. However both Big-endians and Little-endians were downed by the non-progressive element. In 1863 a bill was introduced into Parliament to legalize the French metrical system. Herschel, while favoring decimalisation, did not approve of changing the fundamental units. He argued that the French meter was not the 10,000,000th part of a quadrant of the Earth's meridian passing through Paris, but simply the metre des Archives; and that its authority was precisely of the same kind as the standard yard preserved in London. He also pointed out that the inch was very nearly the 500,500,000th part of the Earth's polar axis, and argued that the polar axis was a better natural unit than an arbitrarily chosen meridian. These arguments are the source of inspiration of Rankine's song about the Three-foot Rule, sang at the British Association. This is the point of contest at the present day both in America and Great Britain; it is not decimalisation but the choice of the fundamental units. The opposition comes from those who do not understand that the whole system of scientific arithmetical calculation for instance in electrical engineering, depends on the choice of the fundamental units; and that whatever the advantages or disadvantages of the fundamental French units, whole systems of derived units have been established upon them, and adopted by international conferences.
Sir John Herschel died at Collingwood on the 11th of May, 1871, in the 80th year of his age. The greatest tribute, in my opinion, to his character is the fact that amid the animosities ​and feuds which troubled the lives and impaired the usefulness of many of the mathematicians of the earlier part of the nineteenth century, Herschel succeeded in retaining the love of all; he was equally the friend of South and Airy, of Babbage and Whewell. His home at Collingwood was the ideal home not of a selfish bachelor wedded to science, but of a devoted husband and loving father. "He never lost his taste for simple amusements; was in his element with children; loved gardening, and took an interest in all technical arts." His family consisted of three sons and nine daughters. His sons have continued, though not in so brilliant a manner, the scientific reputation of the Herschel family. He was buried in Westminster Abbey near the grave of Sir Isaac Newton. On his monument there is his motto Coelis Exploratis and a reference to Psalms CXLV, 4, 5.
Layout 2