FRIENDSHIP WITH STOKES AND JOULE. EARLY WORK AT GLASGOW
During his residence at Cambridge Thomson gained the friendship of
George Gabriel Stokes, who had graduated as Senior Wrangler and First
Smith's Prizeman in 1841. They discussed mathematical questions together
and contributed articles on various topics to the _Cambridge
Mathematical Journal_. In 1846 "Cambridge and Dublin" was substituted
for "Cambridge" in the title of the Journal, and a new series was begun
under the editorship of Thomson. A feature of the earlier volumes of the
new issue was a series of Notes on Hydrodynamics written by agreement
between Thomson and Stokes, and printed in vols. ii, iii, and v. The
first, second, and fifth of the series were written by Thomson, the
others by Stokes. The matter of these Notes was not altogether novel;
but many points were put in a new and more truly physical light, and the
series was no doubt of much service to students, for whose use the
articles were intended. Some account of these Notes will be given in a
later chapter on Thomson's hydrodynamical papers.
For the mathematical power and sure physical instinct of Stokes Thomson
had always the greatest admiration. When asked on one occasion who was
the most outstanding worker in physical science on the continent, he
replied, "I do not know, but whoever he is, I am certain that Stokes is
a match for him." In a report of an address which he delivered in June
1897, at the celebration of the Jubilee of Sir George Stokes as Lucasian
Professor of Mathematics, Lord Kelvin referred to their early
intercourse at Cambridge in terms which were reported as follows: "When
he reflected on his own early progress, he was led to recall the great
kindness shown to himself, and the great value which his intercourse
with Sir George Stokes had been to him through life. Whenever a
mathematical difficulty occurred he used to say to himself, 'Ask Stokes
what he thinks of it.' He got an answer if answer was possible; he was
told, at all events, if it was unanswerable. He felt that in his
undergraduate days, and he felt it more now."
After the death of Stokes in February 1902, Lord Kelvin again referred,
in an enthusiastic tribute in Nature for February 12, to these early
discussions. "Stokes's scientific work and scientific thought is but
partially represented by his published writings. He gave generously and
freely of his treasures to all who were fortunate enough to have an
opportunity of receiving from him. His teaching me the principles of
solar and stellar chemistry when we were walking about among the
colleges sometime prior to 1852 (when I vacated my Peterhouse Fellowship
to be no more in Cambridge for many years) is but one example."
The interchange of ideas between Stokes and Thomson which began in those
early days went on constantly and seems to have been stimulating to
both. The two men were in a sense complementary in nature and
temperament. Both had great power and great insight, but while Stokes
was uniformly calm, reflective, and judicial, Thomson's enthusiasm was
more outspokenly fervid, and he was apt to be at times vehement and
impetuous in his eagerness to push on an investigation; and though, as
became his nationality, he was cautious in committing himself to
conclusions, he exercised perhaps less reserve in placing his results
before the public of science.
A characteristic instance of Thomson's vehement pursuit of experimental
results may be given here, although the incidents occurred at a much
later date in his career than that with which we are at present
concerned. In 1880 the invention of the Faure Secondary Battery
attracted his attention. M. Faure brought from Paris some cells made up
and ready charged, and showed in the Physical Laboratory at Glasgow the
very powerful currents which, in consequence of their very low internal
resistance, they were capable of producing in a thick piece of copper
wire. The cells were of the original form, constructed by coating strips
of sheet lead on both sides with a paste of minium moistened with dilute
sulphuric acid, swathing them in woollen cloth sewed round them, and
then rolling two together to form the pair of plates for one cell.
A supply of sheet lead, minium, and woollen cloth was at once obtained,
and the whole laboratory corps of students and staff was set to work to
manufacture secondary batteries. A small Siemens-Halske dynamo was
telegraphed for to charge the cells, and the ventilating steam-engine of
the University was requisitioned to drive the dynamo during the night.
Thus the University stokers and engineer were put on double shifts; the
cells were charged during the night and the charging current and
battery-potential measured at intervals.
Then the cells were run down during the day, and their output measured
in the same way. Just as this began, Thomson was laid up with an ailment
which confined him to bed for a couple of weeks or so; but this led to
no cessation of the laboratory activity. On the contrary, the laboratory
corps was divided into two squads, one for the night, the other for the
day, and the work of charging and discharging, and of measurement of
expenditure and return of energy went on without intermission. The
results obtained during the day were taken to Thomson's bedside in the
evening, and early in the morning he was ready to review those which had
been obtained during the night, and to suggest further questions to be
answered without delay. This mode of working could not go on
indefinitely, but it continued until his assistants (some of whom had to
take both shifts!), to say nothing of the stokers and students, were
fairly well exhausted.
On other occasions, when he was from home, he found the post too slow to
convey his directions to his laboratory workers, and telegraphed from
day to day questions and instructions regarding the work on hand. Thus
one important result (anticipated, however, by Villari) of the series of
researches on the effects of stress on magnetisation which forms Part
VII of his _Electrodynamic Qualities of Metals_--the fact that up to a
certain magnetising force the effect of pull, applied to a wire of soft
iron, is to increase the magnetisation produced, and for higher
magnetising forces to diminish it--was telegraphed to him on the night
on which the paper was read to the Royal Society.
It will thus be seen that Thomson, whether confined to his room or on
holiday, kept his mind fixed upon his scientific or practical work, and
was almost impatient for its progress. Stokes worked mainly by himself;
but even if he had had a corps of workers and assistants, it is
improbable that such disturbances of hours of attendance and laboratory
and workshop routine would have occurred, as were not infrequent at
Glasgow when Thomson's work was, in the 'sixties and 'seventies, at its
intensest.
Stokes and Thomson were in succession presidents of the Royal Society,
Stokes from 1885 to 1890, and Thomson (from 1892 as Lord Kelvin) from
1890 to 1895. This is the highest distinction which any scientific man
in this country can achieve, and it is very remarkable that there should
have been in recent times two presidents in succession whose modes of
thought and mathematical power are so directly comparable with those of
the great founder of modern natural philosophy. Stokes had the
additional distinction of being the lineal successor of Newton as
Lucasian Professor of Mathematics at Cambridge. But it was reserved for
Thomson to do much by the publication of Thomson and Tait's _Natural
Philosophy_ to bring back the current of teaching and thought in
dynamical science to the ideas of the Principia, and to show how
completely the fundamental laws, as laid down in that great classic,
avail for the inclusion of the modern theory of energy, in all its
transformations, within the category of dynamical action between
material systems.
An exceedingly eminent politician, now deceased, said some years ago
that the present age was singularly deficient in minds of the first
quality. So far as scientific genius is concerned, the dictum was
singularly false: we have here a striking proof of the contrary. But
then few politicians know anything of science; indeed some of those who
guide, or aspire to guide, the destinies of the most scientific and
industrial empire the world has ever seen are almost boastful of their
ignorance. There are, of course, honourable exceptions.
It is convenient to refer here to the share which Stokes and Thomson
took in the physical explanation of the dark lines of the solar
spectrum, and to their prediction of the possibility of determining the
constitution of the stars and of terrestrial substances by what is now
known as spectrum analysis. Thomson used to give the physical theory of
these lines in his lectures, and say that he obtained the idea from
Stokes in a conversation which they had in the garden of Pembroke at
Cambridge, "some time prior to 1852" (see the quotation from his Nature
article quoted above, p. 80, and the _Baltimore Lectures_, p. 101). This
is confirmed by a student's note-book, of date 1854, which is now in the
Natural Philosophy Department. The statements therein recorded are
perfectly definite and clear, and show that at that early date the whole
affair of spectrum analysis was in his hands, and only required
confirmation by experiments on the reversal of the lines of terrestrial
substances by an atmosphere of the substance which produced the lines,
and a comparison of the positions of the bright lines of terrestrial
substances with those of the dark lines of the solar spectrum. Why
Thomson did not carry out all these experiments it would be difficult to
say. Some of them he did make, for Professor John Ferguson, who was a
student of Natural Philosophy in 1859-60, has recently told how he
witnessed Thomson make the experiment of reversing the lines of sodium
by passing the light from the salted flame of a spirit lamp through
vapour of sodium produced by heating the metal in an iron spoon. A few
days later, says Professor Ferguson, Thomson read a letter to his class
announcing Bunsen and Kirchhoff's discovery.
A letter of Stokes to Sir John Lubbock, printed in the _Scientific
Correspondence of Sir George Gabriel Stokes_, states his recollection of
the matter, and gives Thomson the credit of having inferred the method
of spectrum analysis, a method to which Stokes himself makes no claim.
He says, "I know, I think, what Sir William Thomson was alluding to. I
knew well, what was generally known, and is mentioned by Herschel in his
treatise on Light, that the bright D seen in flames is specially
produced when a salt of soda is introduced. I connected it in my own
mind with the presence of sodium, and I suppose others did so too. The
coincidence in position of the bright and dark D is too striking to
allow us to regard it as fortuitous. In conversation with Thomson I
explained the connection of the dark and bright line by the analogy of a
set of piano strings tuned to the same note, which, if struck, would
give out that note, and also would be ready to sound it, to take it up,
in fact, if it were sounded in air. This would imply absorption of the
aërial vibrations, as otherwise there would be a creation of energy.
Accordingly I accounted for the presence of the dark D in the solar
spectrum by supposing that there was sodium in the atmosphere, capable
of absorbing light of that particular refrangibility. He asked me if
there were any other instances of such coincidences of bright and dark
lines, and I said I thought there was one mentioned by Brewster. He was
much struck with this, and jumped to the conclusion that to find out
what substances were in the stars we must compare the positions of the
dark lines seen in their spectra with the spectra of metals, etc....
"I should have said that I thought Thomson was going too fast ahead, for
my notion at the time was that, though a few of the dark lines might be
traced to elementary substances, sodium for one, probably potassium for
another, yet the great bulk of them were probably due to compound
vapours, which, like peroxide of nitrogen and some other known compound
gases, have the character of selective absorption."
It will be remembered that the experimental establishment of the method
of spectrum analysis was published towards the end of 1859 by Bunsen and
Kirchhoff, to whom, therefore, the full credit of discoverers must be
given.
Lord Kelvin in the later years of his life used to tell the story of his
first meeting with Joule at Oxford, and of their second meeting a
fortnight later in Switzerland. He did so also in his address delivered
on the occasion of the unveiling of a statue of Joule, in Manchester
Town Hall, on December 7, 1893, and we quote the narrative on account of
its scientific and personal interest. "I can never forget the British
Association at Oxford in 1847, when in one of the sections I heard a
paper read by a very unassuming young man, who betrayed no consciousness
in his manner that he had a great idea to unfold. I was tremendously
struck with the paper. I at first thought it could not be true, because
it was different from Carnot's theory, and immediately after the reading
of the paper I had a few words with the author, James Joule, which was
the beginning of our forty years' acquaintance and friendship. On the
evening of the same day, that very valuable institution of the British
Association, its conversazione, gave us opportunity for a good hour's
talk and discussion over all that either of us knew of thermodynamics. I
gained ideas which had never entered my mind before, and I thought I,
too, suggested something worthy of Joule's consideration when I told him
of Carnot's theory. Then and there in the Radcliffe Library, Oxford, we
parted, both of us, I am sure, feeling that we had much more to say to
one another and much matter for reflection in what we had talked over
that evening. But ... a fortnight later, when walking down the valley of
Chamounix, I saw in the distance a young man walking up the road towards
me, and carrying in his hand something which looked like a stick, but
which he was using neither as an alpenstock nor as a walking-stick. It
was Joule with a long thermometer in his hand, which he would not trust
by itself in the _char-à-banc_, coming slowly up the hill behind him,
lest it should get broken. But there, comfortably and safely seated in
the _char-à-banc_, was his bride--the sympathetic companion and sharer
in his work of after years. He had not told me in Section A, or in the
Radcliffe Library, that he was going to be married in three days, but
now in the valley of Chamounix he introduced me to his young wife. We
appointed to meet again a fortnight later at Martigny to make
experiments on the heat of a waterfall (Sallanches) with that
thermometer: and afterwards we met again and again, and from that time,
indeed, remained close friends till the end of Joule's life. I had the
great pleasure and satisfaction for many years, beginning just forty
years ago, of making experiments along with Joule which led to some
important results in respect to the theory of thermodynamics. This is
one of the most valuable recollections of my life, and is indeed as
valuable a recollection as I can conceive in the possession of any man
interested in science."
At the beginning of his course of lectures each session, Professor
Thomson read, or rather attempted to read, an introductory address on
the scope and methods of physical science, which he had prepared for his
first session in 1846. It set forth the fact that in science there were
two stages of progress--a natural history stage and a natural philosophy
stage. In the first the discoverer or teacher is occupied with the
collection of facts, and their arrangement in classes according to their
nature; in the second he is concerned with the relations of facts
already discovered and classified, and endeavours to bring them within
the scope of general principles or causes. Once the philosophical stage
is reached, its methods and results are connected and enlarged by
continued research after facts, controlled and directed by the
conclusions of general theory. Thus the method is at first purely
inductive, but becomes in the second stage both inductive and
deductive; the general theory predicts by its deductions, and the
verification of these by experiment and observation give a validity to
the theory which no mere induction could afford. These stages of
scientific investigation are well illustrated by the laws of Kepler
arrived at by mere comparison of the motions of the planets, and the
deduction of these laws, with the remarkable correction of the third
law, given by the theory of universal gravitation. The prediction of the
existence and place of the planet Neptune from the perturbations of
Uranus is an excellent example of the predictive quality of a true
philosophical theory.
The lecture then proceeded to state the province of dynamics, to define
its different parts, and to insist on the importance of kinematics,
which was described as a purely geometrical subject, the geometry
of motion, considerations from which entered into every dynamical
problem. This distinction between dynamical and kinematical
considerations--between those in which force is concerned and those into
which enter only the idea of displacement in space and in time--is
emphasised in Thomson and Tait's _Natural Philosophy_, which commences
with a long chapter devoted entirely to kinematics.
Whether Professor Thomson read the whole of the Introductory Lecture on
the first occasion is uncertain--Clerk Maxwell is said to have asserted
that it was closely adhered to, for that one time only, and finished in
much less than the hour allotted to it. In later years he had never read
more than a couple of pages when some new illustration, or new fact of
science, which bore on his subject, led him to digress from the
manuscript, which was hardly ever returned to, and after a few minutes
was mechanically laid aside and forgotten. Once on beginning the session
he humorously informed the assembled class that he did not think he had
ever succeeded in reading the lecture through before, and added that he
had determined that they should hear the whole of it! But again occurred
the inevitable digression, in the professor's absorption in the new
topic the promise was forgotten, and the written lecture fared as
before! These digressions were exceedingly interesting to the best
students: whether they compensated for the want of a carefully prepared
presentation of the elements of the subject, suited to the wants of the
mass of the members of the class, is a matter which need not here be
discussed. All through his elementary lectures--introductory or not--new
ideas and new problems continually presented themselves. An eminent
physicist once remarked that Thomson was perhaps the only living man who
made discoveries while lecturing. That was hardly true; in the glow of
action and stress of expression the mind of every intense thinker often
sees new relations, and finds new points of view, which amount to
discoveries. But fecundity of mind has, of course, its disadvantages:
the unexpected cannot happen without causing distractions to all
concerned. A mind which can see a theory of the physical universe in a
smoke-ring is likely, unless kept under extraordinary and hampering
restraint, to be tempted to digress from what is strictly the subject in
hand, to the world of matters which that subject suggests. Professor
Thomson was, it must be admitted, too discursive for the ordinary
student, and perhaps did not study the art of boiling down physical
theories to the form most easily digestible. His eagerness of mind and
width of mental outlook gave his lectures a special value to the
advanced student, so that there was a compensating advantage.
The teacher of natural philosophy is really placed in a position of
extraordinary difficulty. The fabric of nature is woven without seam,
and to take it to pieces is in a manner to destroy it. It must, after
examination in detail, be reconstructed and considered as a whole, or
its meaning escapes us. And here lies the difficulty: every bit of
matter stands in relation to everything else, and both sides of every
relation must be considered. In other words, in the explanation of any
one phenomenon the explanation of all others is more or less involved.
This does not mean that investigation or exposition is impossible, or
that we cannot proceed step by step; but it shows the foolishness of
that criticism of science and scientific method which asks for complete
or ultimate knowledge, and of the popular demand for a simple form of
words to express what is in reality infinitely complex.
In the earlier years of his professorship Professor Thomson taught his
class entirely himself, and gathered round him, as he has told us in the
Bangor address, an enthusiastic band of workers who aided him in the
researches which he began on the electrodynamic qualities of metals, the
elastic properties of substances, the thermal and electrical
conductivities of metals, and at a later date in the electric and
magnetic work which he undertook as a member of the British Association
Committee on Electrical Standards. The class met, as has been stated,
twice a day, first for lectures, then for exercises and oral
examination. The changes which took place later in the curriculum, and
especially the introduction of honours classes in the different
subjects, rendered it difficult, if not impossible, for two hours'
attendance to be given daily on all subjects, and students were at first
excused attendance at the second hour, and finally such attendance
became practically optional. But so long as the old traditional
curriculum in Arts--of Humanity, Greek, Logic, Mathematics, Moral
Philosophy and Natural Philosophy--endured, a large number of students
found it profitable to attend at both hours, and it was possible to give
a large amount of excellent tutorial instruction by the working of
examples and oral examination.
Thomson always held that his commission included the subject of physical
astronomy, and though his lectures on that subject were, as a rule,
confined to a statement of Kepler's laws and Newton's deductions from
them, he took care that the written and oral examinations included
astronomical questions, for which the students were enjoined to prepare
by reading Herschel's Outlines, or some similar text-book. This
injunction not infrequently was disregarded, and discomfiture of the
student followed as a matter of course, if he was called on to answer.
Nor were the questions always easy to prepare for by reading. A man
might have a fair knowledge of elementary astronomy, and be unable to
answer offhand such a question as, "Why is the ecliptic called the
ecliptic?" or to say, when the lectures on Kepler had been omitted,
short and tersely just what was Newton's deduction from the third law of
the planetary motions.
Home exercises were not prescribed as part of the regular work except
from time to time in the "Higher Mathematical Class" which for thirty
years or more of Thomson's tenure of office was held in the department.
But the whole ordinary class met every Monday morning and spent the
usual lecture hour in answering a paper of dynamical and physical
questions. As many as ten, and sometimes eleven, questions were set in
these papers, some of them fairly difficult and involving novel ideas,
and by this weekly paper of problems the best students, a dozen or
more perhaps, were helped to acquire a faculty of prompt and brief
expression. It was not uncommon for a good man to score 80 or 90 or even
100 per cent. in the paper, no small feat to accomplish in a single
hour. But to a considerable majority of the class, it is doubtful
whether the weekly examination was of much advantage: they attempted
one or two of the more descriptive questions perhaps, but a good
many did next to nothing. The examinations came every week, and so
the preparation for one after another was neglected, and as much
procrastination of work ensued as there would have been if only four or
five papers a session had been prescribed. Then the work of looking over
so many papers was a heavy task to the professor's assistant, a task
which became impossible when, for a few years in the early 'eighties,
the students in the ordinary class numbered about 250.
The subject of natural philosophy had become so extensive in 1846 that
Professor J. P. Nichol called attention to the necessity for special
arrangements for its adequate teaching. What would he say if he could
survey its dimensions at the present time! To give even a brief outline
of the principal topics in dynamics, heat, acoustics, light, magnetism,
and electricity is more than can be accomplished in any course of
university lectures; and the only way to teach well and economically the
large numbers of students[16] who now throng the physics classes is to
give each week, say, three lectures as well considered and arranged as
possible, without any interruption from oral examination, and assemble
the students in smaller classes two or three times a week for exercises
and oral examination.
Thomson stated his views as to examinations and lectures in the Bangor
address. "The object of a university is teaching, not testing, ... in
respect to the teaching of a university the object of examination is to
promote the teaching. The examination should be, in the first place,
daily. No professor should meet his class without talking to them. He
should talk to them and they to him. The French call a lecture a
conférence, and I admire that idea. Every lecture should be a conference
of teachers and students. It is the true ideal of a professorial
lecture. I have found that many students are afflicted when they come up
to college with the disease called 'aphasia.' They will not answer when
questioned, even when the very words of the answer are put in their
mouths, or when the answer is simply 'yes' or 'no.' That disease wears
off in a few weeks, but the great cure for it is in repeated and careful
and very free interchange of question and answer between teacher and
student.... Written examinations are very important, as training the
student to express with clearness and accuracy the knowledge he has
gained, but they should be once a week to be beneficial."
The great difficulty now, when both classes and subject have grown
enormously, is to have free conversation between professor and student,
and yet give an adequate account of the subject. To examine orally in a
thorough way two students in each class-hour is about as much as can be
done if there is to be any systematic exposition by lecture at all; and
thus the conference between teacher and individual student can occur
only twice a year at most. Nevertheless Lord Kelvin was undoubtedly
right: oral examination and the training of individual students in the
art of clear and ready expression are very desirable. The real
difficulties of the subject are those which occur to the best students,
and a discussion of them in the presence of others is good for all. This
is difficult nowadays, for large classes cannot afford to wait while two
or three backward students grope after answers to questions--which in
many cases must be on points which are sufficiently plain to the
majority--to say nothing of the temptation to disorder which the display
of personal peculiarities or oddities of expression generally affords to
an assembly of students. But time will be economised and many advantages
added, if large classes are split up into sections for tutorial work, to
supplement the careful presentation of the subject made in the
systematic lectures delivered to the whole class in each case. The
introduction of a tutorial system will, however, do far more harm than
good, unless the method of instruction is such as to foster the
self-reliance of the student, who must not be, so to speak, spoon-fed:
such a method, and the advantages of the weekly examination on paper
may be secured, by setting the tutorial class to work out on the spot
exercises prescribed by the lecturer. But the danger, which is a very
real one, can only be fully avoided by the precautions of a skilful
teacher, who in those small classes will draw out and direct the ideas
of his students, rather than impart knowledge directly.
After a few years Thomson found it necessary to appoint an assistant,
and Mr. Donald McFarlane, who had distinguished himself in the
Mathematics and Natural Philosophy classes, was chosen. Mr. McFarlane
was originally a block-printer, and seems to have been an apprentice at
Alexandria in the Vale of Leven, at the time of the passing of the first
Reform Bill. After some time spent in the cotton industry of the
district, he became a teacher in a village school in the Vale of Leven,
and afterwards entered the University as a student. He discharged his
duties in the most faithful and self-abnegating manner until his
retirement in 1880, when he had become advanced in years. He had charge
of the instruments of the department, got ready the lecture
illustrations and attended during lecture to assist in the experiments
and supply numerical data when required, prepared the weekly class
examination paper and read the answers handed in, and assisted in the
original investigations which the professor was always enthusiastically
pursuing. A kind of universal physical genius was McFarlane; an expert
calculator and an exact and careful experimentalist. Many a long and
involved arithmetical research he carried out, much apparatus he made in
a homely way, and much he repaired and adjusted. Then, always when the
professor was out of the way and calm had descended on the
apparatus-room, if not on the laboratory, McFarlane sat down to reduce
his pile of examination papers, lest Monday should arrive with a new
deluge of crude answers and queer mistakes, ere the former had
disappeared. On Friday afternoons at 3 o'clock he gave solutions of the
previous Monday's questions to any members of the class who cared to
attend; and his clear and deliberate explanations were much appreciated.
An unfailing tribute was rendered to him every year by the students, and
often took the form of a valuable gift for which one and all had
subscribed. A recluse he was in his way, hardly anybody knew where he
lived--the professor certainly did not--and a man of the highest ability
and of the most absolute unselfishness. An hour in the evening with one
or two special friends, and the study of German, were the only
recreations of McFarlane's solitary life. He was full of humour, and
told with keen enjoyment stories of the University worthies of a bygone
age. For thirty years he worked on for a meagre salary, for during the
earlier part of that time no provision for assistants was made in the
Government grant to the Scottish Universities. By an ordinance issued in
1861 by the University Commissioners, appointed under the Act of 1858, a
grant of £100 a year was made from the Consolidated Fund for an
assistant in each of the departments of Humanity, Greek, Mathematics,
and Natural Philosophy, and for two in the department of Chemistry; and
McFarlane's position was somewhat improved. His veneration for Thomson
was such as few students or assistants have had for a master: his
devotion resembled that of the old famulus rather than the much more
measured respect paid by modern assistants to their chiefs.
After his retirement McFarlane lived on in Glasgow, and amused himself
reading out-of-the-way Latin literature and with the calculation of
eclipses! He finally returned to Alexandria, where he died in February
1897. "Old McFarlane" will be held in affectionate remembrance so long
as students of the Natural Philosophy Class in the 'fifties and 'sixties
and 'seventies, now, alas! a fast vanishing band, survive.
Soon after taking his degree of B.A. at Cambridge in 1845, Thomson had
been elected a Fellow of St. Peter's College. In 1852 he vacated his
Fellowship on his marriage to Miss Margaret Crum, daughter of Mr. Walter
Crum of Thornliebank, near Glasgow, but was re-elected in 1871, and
remained thereafter a Fellow of Peterhouse throughout his life.