John Michell

The world of today has almost forgotten John Michell, but no more bold and original thinker ever devoted himself to the study of the earth or the heavens. He lived at a time immediately preceding the advent of William Smith and Sir William Herschel, and his greatness has been kept in the background by the honour which the world has awarded to his successors. … To a certain extent this is due to the fact that Michell’s speculations were a full century before his age.
^{[The Rev. John Michell, Astronomer and Geologist, by John Richard Sutton (1865–​1937), in Knowledge : an Illustrated Magazine of Science, Vol. XV (n.s. vol. VII), No. 84, 1892 October, p. 188]} 

The century which elapsed between the death of Newton ^[1727] and the scientific activity of Green ^[1828] was the darkest in the history of the University. … In the entire period the only natural philosopher of distinction who lived and taught at Cambridge was Michell; and for some reason which at this distance of time is difficult to understand fully, Michell’s researches seem to have attracted little attention among his collegiate contemporaries and successors who silently acquiesced when his discoveries were attributed to others, and allowed his name to perish entirely from Cambridge tradition.
^{[A history of the theories of aether and electricity, by Sir Edmund Taylor Whittaker, 1910, pp. 167–​8 (OCLC 1963779)]} 

Over a century later, Michell’s name still does not command the widespread recognition that it deserves.

[In what follows, if a date between January 1st and March 24th is written in the year “1748/9”, then this means that the day occurred in the year 1748 in the Julian calendar, then used for record-keeping, in which the year number advances by one on March 25th. In the modern Gregorian calendar, the year would be considered to be 1749.]

John Michell was born on Christmas Day 1724, in the parish of Eakring, Nottinghamshire ^{[Parish register, Crossley 2003 p.5]}, where his father Gilbert was Rector 1722–​58 ^[CCEd][ACAD]. His mother was Obedience Gerrard, originally from London.

Michell was admitted as a pensioner ^{[a student, not in possession of a scholarship, who pays for tuition, accommodation, and food]} to Queens’ College 1742 June 17 ^[ACAD], and matriculated later in 1742, probably in the Michaelmas Term. He took the Mathematical Tripos examination in January 1748/9 and was ranked 4th Wrangler ^{[Historical Register 1917 p. 444]}. If normal university practice ^{[Historical Register 1917 p. 351]} was followed, he would have graduated BA on Ash Wednesday in February 1748/9. [This was a much longer period than normally taken from matriculation to graduation: it is possible that Michell was not in residence for all this time.]

A necessary prerequisite to being elected to a fellowship was being in holy orders. Michell was ordained deacon 1748/9 February 19 ^[CCEd], and licensed as a curate 1748/9 February 20 in his father’s parish of Eakring. He was elected a Fellow of Queens’ College 1749 March 30 ^{[Geikie 1918 p. 4]}, only a few weeks after graduation.

In 1750, Michell published A treatise of artificial magnets, in which he was the first person to state the inverse-square law of magnetic action. He also identified the relevant point from which to measure distances as being the magnetic pole, rather than the centre of the magnet (this being a difference between magnetism and gravity). Earlier investigators had mostly failed to identify any underlying law of action, or had stated it incorrectly (Newton at one point thought it to be inverse-cube). Michell did not publish any experimental method or data for verifying his statements about the properties of magnetism. His statements on the properties of magnetism seem to have been largely ignored by the scientific community, and the person normally attributed with first stating the inverse-square law of magnetic action is Coulomb, who published the law and the experimental methods he used in the 1780/90s period.

Michell graduated M.A. in 1752.

In 1760, Michell read a paper to the Royal Society, spread over five sessions, on an analysis of the Lisbon earthquake of 1755. Although his theory of the originating cause (a steam explosion) of an earthquake was incorrect, he was the first person to correctly observe that earthquakes propagated as waves in a compressible and elastic earth, a novel concept. He was able to estimate the location of the epicentre of the earthquake. He also demonstrated an extensive knowledge of geological strata, apparently from his own personal observations, and noted the existence of fault-lines in strata. His stratigraphic knowledge, somewhat before its time, was largely ignored, and was overshadowed by the later work of William Smith.

Early in 1760, a vacancy arose for the living of St Botolph’s parish in Cambridge. Queens’ College, situated within St Botolph’s parish, is patron of that living. At that period, it was the practice that, whenever a living fell vacant at any of the parishes of which the college was patron, then that living was offered to the most senior eligible Fellow not already in possession of a parish. This was the offer of a paid job for life: it was an offer difficult to refuse. When used in combination with resignation of the fellowship, it offered an escape route from the enforced celibacy of that fellowship, and such resignations helped to keep the fellowship reasonably young. In 1760, it was Michell’s turn to be in line for a parish living. Michell was ordained priest 1760 May 6 ^[CCEd], and instituted Rector of St Botolph’s 1760 May 31 ^[CCEd], in parallel with his Fellowship. There was no rectory house for St Botolph’s, so presumably Michell remained living in college, still subject to the celibacy rule.

He was elected a Fellow of the Royal Society on 1760 June 12 ^{[Royal Society archives EC/1760/06]}.

In November 1760, Michell met with Roger Joseph Bošković while the latter was visiting Cambridge. Bošković noted in his diary that he met Mr Michel who does magnetic experiments. ^{[Roger Joseph Boscovich, by L.L. White, 1961, opp p. 64]}.

Boscovich had frequent discussions with John Michell who demonstrated to him the artificial magnetization of solid bars, and discussed with Boscovich his theory of ‘molecular magnets’. Michell also believed that repulsive forces must appear at very small distances.
^{[ibid., p. 130, quoting letter from Boscovich to his brother]} 

By college statutes ^{[Chapter 32]}, fellows were obligated to continue their studies so as to graduate B.D. nine years after their M.A., or forfeit their fellowship. Accordingly, Michell graduated B.D. in 1761, on schedule.

It is probably to this period, or later, that we can attribute a note about Michell by the diarist and antiquary William Cole, who wrote:

John Michell, BD is a little short Man, of a black Complexion, and fat; but having no Acquaintance with him, can say little of him. I think he had the Care of of St Botolph’s Church, while he continued Fellow of Queen’s College, where he was esteemed a very ingenious Man, and an excellent Philosopher. He has published some Things in that way, on the Magnet and Electricity.
^{[Cole MSS xxxiii, 156 (BL Add. MSS. 5834), quoted in (a) Adam Sedgwick, by Clark & Hughes, 1890, p. 192; (b) Geike 1918 p. 8]} 

Michell was elected Woodwardian Professor of Geology (then called Fossils) by the university in 1762 ^{[Historical Register, 1917, p. 91]}, probably on the strength of his 1760 earthquake paper.

Michell was collated to be Rector of Compton, Hampshire, 1763 April 7 ^[CCEd].

1763. John Michell collated to the rectory of Compton …. Mr. Michell retained the benefice for less than two years, and it is doubtful whether he ever lived here; all the parochial records are in the handwriting of Dr. Shipman.^{[the curate]
[Compton, near Winchester, by John Summers Drew, 1939, p. 121, (OCLC 12271319)]} 

John Michell was instituted rector in April, 1763, he allowed Dr. Shipman ^{[the curate]} to carry on the work of the parish, he spent £111 on re-tiling and repairing the rectory and he left in January, 1765, on being appointed rector of Havant.
^{[Compton Clergy of Long Ago, by John Summers Drew, Part 8, in Compton Parish Magazine, 1934 August]} 

In 1764 he left both his college fellowship and the Woodwardian Professorship, both of which required the office-holder to remain celibate. He married Sarah Williamson 1764 August 23 at Rolleston, Nottinghamshire (about 12 miles by road from Eakring) ^[FreeREG]:

A Few days ago the Rev. Mr Michell, Rector of Compton, near Winchester, late Fellow of Queen’s College, and Woodwardian Professor of Fossils in this University, was married to Miss Williamson, a young Lady of considerable fortune near Newark in Nottinghamshire.
^{[Cambridge Chronicle, Vol. 2, No. 98, 1764 September 8, p. 3]} 

John Michell Clerk Rector of the Parish of Compton in y^e County of Hants aged above 39 years & a Batchelor and Sarah Williamson of this Parish aged above 30 years were married … Aug. 23. 1764.
^{[transcript of parish register in Names Book, p. 13]} 

Sarah was the daughter of Luke Williamson and Sutton (née Holmes), and had been baptised 1727 October 19 at Rolleston. She had been previously married ^{[McCormmach 2012 p. 118]}.

Michell was collated to be Rector of Havant, Hampshire, 1765 January 23 ^[CCEd].

The Rev. John Michell B.D. was inducted on the 1st February 1765. … As rector he was in every respect a worthy character and was much esteemed by his parishioners.
^{[A Topographical Account of the Hundred of Bosmere, by Charles John Longcroft, 1857, p. 55. (OCLC 23379811)]} 

Michell’s only child, Mary, was born 1765 August 1 ^{[New Baronetage of England, 1804, Vol. 2, p. 894]}, and baptised 1765 September 3 at Newark ^[FreeREG]. But his wife Sarah died 1765 September 18 ^{[memorial at Rolleston parish church, transcribed in their Names Book, p. 18]}, and was buried 1765 September 20 at Rolleston ^[FreeREG].

In 1763, 1765, and 1770, he was called upon by the Board of Longitude to serve on committees evaluating certain chronometers, including the Harrison H-4.^{[McCormmach 2012 p. 120]} The fact that he was appointed to these positions is some indication of the respect which his contemporaries had for his scientific and technical abilities. In this period he also published two minor papers on Hadley’s Quadrant (1765) and a method of measuring longitude (1766).

In 1767 he published his most important paper An Inquiry into the probable Parallax, and Magnitude of the fixed Stars, from the Quantity of Light which they afford us, and the particular Circumstances of their Situation. This paper divides into three parts. In the first part, Michell provides a method of estimating the distance of the stars, based upon some assumptions, which he states (such as assuming that all stars have roughly the same brightness as our sun). He notes that many visible stars appear about as bright in our sky as the planet Saturn, which is of a known distance. He then sets about calculating an answer to the question: how far away would a star like the sun have to be, to have as little brightness as Saturn when viewed from the earth? This was the first ever realistic estimation of the distance of the stars: his answer was only about 4 times too small: a remarkable achievement in that era. In the second part, he addresses the issue of apparent double or multiple stars: whether they are physically unrelated and an accident of parallax in the heavens, or whether they are genuinely physically close to each other. In the first ever application of statistical methods to astronomy, he computed an overwhelming probability that multiple stars are indeed physically close to each other, and probably bound together by their gravitation. He concluded:

We may from hence, therefore, with the highest probability conclude (the odds against the contrary opinion being many million millions to one) that the stars are really collected together in clusters in some places, where they form a kind of systems, whilst in others there are either few or none of them, to whatever cause this may be owing, whether to their mutual gravitation, or to some other law or appointment of the Creator. And the natural conclusion from hence is, that it is highly probable in particular, and next to a certainty in general, that such double stars, &c. as appear to consist of two or more stars placed very near together, do really consist of stars placed near together, and under the influence of some general law, whenever the probability is very great, that there would not have been any such stars so near together, if all those, that are not less bright than themselves, had been scattered at random through the whole heavens.

In other words, he predicted that there would be a great many real binary stars to be discovered. The third part of the paper speculated on whether our own sun might be a member of a star system, and, if so, how one might determine which visible stars are those in the sun’s own system, and which are not. (In this dicussion, he does not mention the Milky Way, so apparently he never knew of, or made, that connection). He also pointed out that whether a telescope can see the weaker stars is a question of the aperture of the lens (or mirror) and not the magnification factor of the device. Michell’s theoretical prediction of binary stars in 1767 was largely overshadowed by William Herschel’s publications of actual binary star observations from 1779 onwards, and Herschel’s fame arising from his discovery of the planet Uranus in 1781.

On 1767 October 3, Michell was instituted as Rector of the parish of Thornhill, West Yorkshire, where the patron of the parish living was Sir George Savile, 8th Baronet, his childhood friend and contemporary at Queens’ College Cambridge (just as Savile’s father had presented Michell’s father to Eakring, another parish in the gift of the Saviles). Michell made Thornhill his home for the rest of his life, and continued his scientific researches there. He married a second time, to Ann Brecknock, at Newark, 1773 Feb 13 ^[FreeREG]. There appear to have been no children from this marriage.

During this period, his researches are documented mainly in private letters to his friend Henry Cavendish, and to Joseph Priestley. In particular, there are several references to Michell, his beliefs and theories, in Priestley’s published work ^{[The History and Present State of Discoveries relating to Vision, Light, and Colours, by Joseph Priestley, 1772, Vol. 1; Vol. 2]}. From those, it appears that Michell held beliefs on the structure of matter very similar to those of Bošković, although Priestley asserted that Michell arrived at his theories independently.

In 1783, Michell’s paper On the Means of discovering the Distance, Magnitude, &c. of the Fixed Stars, in consequence of the Diminution of the Velocity of their Light, … was read to the Royal Society. Following the Newtonian principle of the corpuscular theory of light, and assuming the universality of the action of gravity, he pointed out that light particles emitted by a star should be slowed down by the gravitational field of that star, and the greater the mass of the star, the more the light particles should be slowed. The varying speeds of light particles from different stars might be detectable by the differing extent of their refraction by a prism, and thus the masses of the stars might be inferred, if stars existed of a large enough mass that the change in refraction was large enough to be experimentally detectable. Almost as an aside (it not being the main thrust of the paper), he observed that a star of the same density of the sun, but 497 times larger in diameter, would have a gravitational field so strong that any emitted light particle would be dragged back into the star: the star would thus not be visible from a distance. He provided a geometrical justification of this assertion. Later in the paper he made the point:

If there should really exist in nature any bodies, whose density is not less than that of the sun, and whose diameters are more than 500 times the diameter of the sun, since their light could not arrive at us; or if there should exist any other bodies of a somewhat smaller size which are not naturally luminous; of the existence of bodies under either of these circumstances, we would have no information from sight; yet, if any other luminous bodies should happen to revolve about them we might still perhaps from the motions of these revolving bodies infer the existence of the central ones with some degree of probability, as this might afford a clue to some of the apparent irregularities of the revolving bodies, which would not be easily explicable on any other hypothesis; …

That was a good prediction of how modern astronomers detect the presence of massive non-luminous objects, or of black holes. Michell, in his writings, did not coin any name (such as dark star) for these massive objects: all such phrases have been retro-fitted by later writers. Michell’s speculations on such invisible stars were subsequently overshadowed by similar claims made by Pierre-Simon Laplace:

Un astre lumineux de même densité que la terre, et dont le diamètre serait deux cents cinquante fois plus grand que celui du soleil, ne laisserait en vertu de son attraction, parvenir aucun de ses rayons jusqu’à nous; il est donc possible que les plus grands corps lumineux de l’univers, soient par cela même, invisibles.
^{[Exposition du système du monde, by Pierre-Simon Laplace, 1st edition 1796, Vol. II, Book V, Ch. VI, p. 305; 2nd edition 1799, p. 348; omitted from later editions]} 

In 1799, Laplace provided a mathematical justification for his 1796 claim ^{[Allgemeine geographische Ephemeriden, Vol. 4, pp. 1–​6]}. Both Michell’s and Laplace’s speculations on invisible stars were invalidated during the 19th century by the abandonment of the corpuscular theory of light in favour of the wave theory, which did not provide for a light wave to interact with a gravitational field. However, with the development of General Relativity in the 20th century, the possibility of light being affected by a gravitational field returned, in a different form. Also, General Relativity permitted the existence of singularities in space-time, such as large masses in an infinitesimal point, for which the term black hole became popularised after 1968. Black holes could capture light (and anything else). The invisible massive luminous objects imagined by Michell and Laplace were not black holes as such, but they occupied a quasi-analogous position in the Newtonian corpuscular universe, as do black holes in the General Relativistic universe. The first person to note the analogy between Michell’s speculations and modern black holes appears to have been Stanley L. Jaki in 1978 ^{[Jaki 1978 p. 936n15]}, followed closely by Simon Schaffer ^{[John Michell and Black Holes, Schaffer 1979]}, the latter gaining more public attention. Thus began the legends that Michell, back in 1783, had (in loose language) predicted the discovery of black holes.

Throughout the 1780s, Michell expended much effort on building himself a large reflecting telescope. The mirror, which he ground himself, was nearly 30 inches (76 cm) in diameter, and the body was 12 feet (3·7 m) long. After his death, the telescope was purchased from his executor by William Herschel: see below.

Michell’s only child, Mary, was married at Thornhill to Thomas Turton, 1786 September 2 ^[FreeREG]. Turton was at that time an undergraduate at Jesus College, Cambridge ^[ACAD]. He would later become Michell’s executor, and, in 1796, a Baronet ^{[New Baronetage of England, 1804, Vol. 2, p. 894]}.

John Michell died 1793 April 21 ^{[memorial at Thornhill parish church]}, and was buried 1793 April 27 at Thornhill ^[FreeREG]. He was survived (a) by his second wife Ann, who died 1818 November 3 ^[gravestone], and was buried November 6 at Thornhill ^{[parish register]}, and (b) by his daughter (by his first wife), Mary, who died 1837 January 28 ^{[memorial at Lingfield parish church, Surrey]}.

At some point in his life, Michell invented and built what is now called a torsion balance, as part of his planned experiment to measure the density of the earth. The invention of the torsion balance is normally credited to Coulomb, who used a torsion balance in his investigation of the inverse-square law of electrostatic action, as described in 1785 ^{[Premier Mémoire sur l'Électricité et le Magnétisme, with diagram, by Charles Coulomb, 1785, in Mémoires de l'Académie royale des sciences, vol. 88, pp. 569–​577, published 1788]}. Michell constructed a torsion balance, but never carried out the planned experiment before his death. After his death, Michell’s apparatus, suitably modified, was famously used by Henry Cavendish to carry out the Cavendish Experiment to measure the density of the earth (which would now be regarded as an experiment to determine the gravitational constant G). Cavendish wrote:

Many years ago, the late Rev. John Michell, of this Society, contrived a method of determining the density of the earth, by rendering sensible the attraction of small quantities of matter; but, as he was engaged in other pursuits, he did not complete the apparatus till a short time before his death, and did not live to make any experiments with it. After his death, the apparatus came to the Rev. Francis John Hyde Wollaston, Jacksonian Professor at Cambridge, who, not having conveniences for making experiments with it, in the manner he could wish, was so good as to give it to me.
^{[Experiments to determine the Density of the Earth, by Henry Cavendish, in Phil. Trans. R. Soc. Lond. 1798 Vol. 88 pp. 469–​526, at p. 469]} 

Mr. Coulomb has, in a variety of cases, used a contrivance of this kind ^{[torsion balance]} for trying small attractions; but Mr. Michell informed me of his intention of making this experiment, and of the method he intended to use, before the publication of any of Mr. Coulomb’s experiments.
^{[ibid. p. 470n]} 

So we have Cavendish’s published word that Michell had conceived of a torsion balance before Coulomb published his descriptions. Cavendish and Michell are known to have exchanged letters about Michell’s intended experiment in 1783 ^{[McCormmach 2012 p. 277]}, and had probably talked about it prior to that. It is not known how Michell’s torsion balance came into Wollaston’s possession [unless Wollaston was the “man of science, & acknowledged talent in the world” referred to in Turton’s second letter to Herschel, below].

In 1871, the periodical English Mechanic and World of Science published a letter signed by Khoda Bux purporting to give fresh information on William Herschel and John Michell ^{[Sir William Herschel, by Khoda Bux, in English Mechanic and World of Science, Vol. 13, No. 325, 1871 June 16, pp. 309–​10]}. The letter has been transcribed and analysed twice ^{[Geikie 1918 pp. 13–​19, Hutton 2006]}: some assertions in that letter, when put to the test against established history, have been shown to be false. The author Khoda Bux has been identified as Andrew Thomas Turton Peterson, a great-grandson of John Michell. The contents of the letter were his recollections of oral tradition passed down within the family: it appears that those oral traditions, or his memory, were flawed. With some of his statements being verifiably false, doubt is then cast on his other statements which, though plausible, cannot be independently verified. It would be safer not to rely on anything which is single-sourced in his letter. However, the damage has already been done: the entry for John Michell in the original Dictionary of National Biography (1894) accepted almost everything in the letter as worthy of report, even reproducing some phrases verbatim, for instance: … was no mean violinist. Many subsequent biographies of John Michell have reproduced uncritically from the DNB statements which were, at worst, false, or, at best, unverifiable. Even the new Oxford DNB has inherited falsehoods from its earlier edition.

The first modern re-appraisal of Michell’s work was The Scientific Work of the Reverend John Michell ^{[Hardin 1966]}, where the final summing up was:

Putting aside most of Michell’s unpublished scientific researches, we are faced with the problem of why his published work has not received the attention that it deserves. … His theoretical grasp of the magnet was largely hidden by his emphasis on the practical value of his method of making artificial magnets … and he never published the experimental grounds for the principles he enunciated. He had virtually all the ingredients necessary for a fundamentally correct understanding of the origin and character of earthquakes, but he was unable to arrange them in the proper fashion. His argument for the existence of physical stellar binaries was ingenious and persuasive, but it was Herschel who actually discovered them. His theory of matter was mentioned in conversation, but never systematically developed and published. His apparatus for measuring the momentum of light was never completed, and he was unable to use his great torsion balance, the successful employment of which for the measurement of the mass of the earth would have been enough in itself to bring Michell lasting fame. Thus none of Michell’s work was fully developed, promoted, and secured by him. It appears, then, that he was in great measure responsible for the unjust obscurity into which his reputation has fallen.

On 2007 September 8, a blue plaque commemorating John Michell was unveiled on Thornhill parish church.

Postscript

Almost every biography of Michell includes a statement of the form: His scientific instruments were presented after his death to Queens’ College, Cambridge.

The problems with that statement are: (a) that there is no reliable authority for the assertion itself; and (b) that no record has been found at Queens’ College of such a presentation ever having been received. The statement seems to have been copied uncritically from one biography to another. The earliest occurrence of this assertion lies in the notorious letter from Khoda Bux of 1871 (see above). In cases where the Khoda Bux letter is the only source of a claim, with no independent substantiation, we should be cautious about accepting that source as a reliable authority. The author of the original 1894 DNB entry for Michell, Agnes Mary Clerke, seems to have taken the Khoda Bux letter largely at face value, and reproduced the statement about the scientific instruments being presented to the college. Later biographies copied from the DNB. The statement is unverifiable. It is possible that no such presentation was ever made.

In his will, Michell bequeathed all his possessions to his Executor, his son-in-law Thomas Turton. The little we know about how Turton disposed of the scientific instruments is contained in two letters that Turton wrote to William Herschel in 1793. In the first:

… I must introduce my business by informing you that as Legatee & Executor of my late father in law, M^r Michell, all his mechanical apparatus & instruments have fallen into my hands. It is natural I should wish in the disposal of them, as well as on my own account as out of respect to the memory of the deceased, that they should fall into such hands as are most likely to do them credit & in this wish I have in general been much gratified by applications from men of science & knowledge in the particular branches for which the instruments were suited - but for one article we have been at a loss to know, where we can look to for the disposal of it & that is the large Telescope which occupied for the space of some years, a great deal of M^r Michell’s time & attention. The progress which has been made (so truly to the advantage of science) by you in that particular branch, points you out as the most proper person, to apply to on the occasion - & I should much sooner have done it, could I have conquered the reluctance I felt, to trouble a gentleman, whose acquaintance (saving a slight personal knowledge of) I have not the honor of possessing. If you could in any degree assist me with your advice, as to the best mode of disposing of it, (as its magnitude & the circumstance of the living of Thornhill being already given away will oblige me, if I can manage no better, to knock it in pieces, & sell it for old materials) I shall think myself extremely indebted to you. The dimensions & state of the Telescope are nearly as follows. A Reflecting Telescope Tube 12 ft long - made of Rolled Iron, painted inside & out, & in good preservation. The Diameter of the large speculum 29 inch - Focal length 10 feet - its weight is 330^lb:- it is now cracked. There are also 3^[?] concave small mirrors of different sizes viz of 3¼ - 4 & 5 inch diam^r - and 2 convex mirrors 3¼ inch diam^r - they are polished. There are also [?] sets of Eye Glasses in brass tubes & cells. The weight of the whole is about half a tun. …
^{[Herschel MSS W1/13 T.10]} 

Judging by the second letter, Herschel had responded expressing a personal interest in acquiring the telescope. Turton replied:

… Since I wrote to you, a letter has been sent to me by a man of science, & acknowledged talent in the world, desiring the refusal of the apparatus & mechanical instruments of the late M^r Michell of which he has begged an inventory - I do hope from the respect he had to M^r M’s memory, & the value he set on any experiments of his, (however as to their effect rendered useless by subsequent improvements) he will be inclined to take the Telescope in question, at a price somewhat exceeding the value of the old Materials, which have had the price of £26 fixed on them to break up & which the Rotherham Iron Masters, would be willing to give for them. I have mentioned to this gentleman my application to you, & as a friend to science he is well inclined to waive treating for the instrument till he knows your determination convinced how much he is assisting the cause of Philosophy in so doing. ...
^{[Herschel MSS W1/13 T.11]} 

Herschel paid £30 for the telescope (possibly over £4000 at today’s values). In this case, Turton’s concern seems to have been the realisable cash value of the apparatus. Michell’s papers were not preserved for posterity: if Turton took them away, then they were lost later. It only remains to wonder who the unnamed man of science, & acknowledged talent in the world was, and whether he did take the rest of Michell’s collection.

Memorial to John Michell at Thornhill

In the Chancel of this Church are deposited, the
Remains of The Rev^d. Jⁿ. Michell B.D, F.R.S,
& 26 years Rector of this Parish.
Eminently distinguished as the Philosopher, & the
Scholar, He had a just claim to the character of the
Real Christian. In the relative and social Duties of Life:
The tender husband, the indulgent Parent,
the affectionate brother, & the sincere Friend,
were prominent Features in a character uniformly
amiable. His charities were not those of ostentation,
but of feeling. His strict discharge of his professional
duties, that of principle, not form. As he lived in possession
of the esteem of his Parishioners, so he has carried with
him to the grave their regret.
He died the 21^st. April 1793, in the 69^th. Year of his Age.

Memorial to Sarah Michell at Rolleston

To the Memory of
Mary Williamson who
Died June 27^th. 1761
Aged 27 Years
And of Sarah, Wife of the
Rev. John Michell
who Died Sep^r. 18^th. 1765
Aged 38 Years
Daughters of Luke
& Sutton Williamson

Memorial to Thomas & Mary Turton at Lingfield

IN A VAULT
BENEATH THIS TABLET
ARE INTERRED THE MORTAL REMAINS
OF SIR THOMAS TURTON, BART.
LATE OF FELCOURT IN THIS PARISH,
THIRD SON OF WILLIAM TURTON ESQUIRE
OF SONDES, IN THE COUNTY OF BERKS.
HE DIED APRIL 17,1844, IN THE 80TH YEAR OF HIS AGE.
ALSO OF
DAME MARY TURTON
WIFE OF THE ABOVE
ONLY CHILD OF THE REVD. JOHN MICHELL
RECTOR OF THORNHILL, COUNTY OF YORK.
SHE DIED JANY. 28,1837, IN THE 72ND YEAR OF HER AGE.

Links

• Entry for John Michell in A Cambridge Alumni Database.
• Entry for John Michell in the Clergy of the Church of England Database.
• Entry for John Michell in the Royal Society archives.
• Subsequent history of the Turton baronets.

Further reading

1750: A treatise of artificial magnets; in which is shewn an easy and expeditious method of making them, by John Michell ^[Fellow]; (OCLC 79533222)
1751: Second edition, corrected and improved; (OCLC 30552768)
1752: Edition in French, in Traités sur les aimans artificiels: contenant une méthode courte et aisée pour les composer, tr. by Antoine Rivoire. (OCLC 264953481)

1750: A Treatise of Artifical Magnets. By J. Michell, in The Monthly Review, Vol. 2, 1750 March, pp. 417–​423. (OCLC 656868867) [review of above] 

1760: Observations on the same Comet, by John Michell, in Phil. Trans. 1759 Vol. 51 pp. 466–​467. (ISSN 0260-7085)

1760: Conjectures concerning the Cause, and Observations upon the Phænomena of Earthquakes; particularly of that great Earthquake of the First of November, 1755, which proved so fatal to the City of Lisbon, and whose Effects were felt as far as Africa and more or less throughout almost all Europe, by John Michell, in Phil. Trans. 1759 Vol. 51 pp. 566–​634; (ISSN 0260-7085)
1760: Conjectures concerning the cause, and observations upon the Phænomena, of earthquakes, by John Michell. (OCLC 23636465)

1765: A Recommendation of Hadley’s Quadrant for surveying, especially the surveying of Harbours, together with a particular Application of it in some Cases of Pilotage, by John Michell, in Phil. Trans. 1765 Vol. 55 pp. 70–​78. (ISSN 0260-7085)

1766: Proposal of a Method for measuring Degrees of Longitude upon Parallels of the Æquator, by John Michell, in Phil. Trans. 1766 Vol. 56 pp. 119–​125. (ISSN 0260-7085)
1767: Proposal of a Method for Measuring Degrees of Longitude upon Parallels of the Æquator, by John Michell. (OCLC 1227607601)

1767: An Inquiry into the probable Parallax, and Magnitude of the fixed Stars, from the Quantity of Light which they afford us, and the particular Circumstances of their Situation, by John Michell, in Phil. Trans. 1767 Vol. 57 pp. 234–​261. (ISSN 0260-7085)
1768: An Inquiry into the probable Parallax, and Magnitude of the fixed Stars, from the Quantity of Light which they afford us, and the particular Circumstances of their Situation, by John Michell. (OCLC 1063120592)

1767: Of the twinkling of Fixed Stars, by John Michell, in Phil. Trans. 1767 Vol. 57 pp. 261–​264. (ISSN 0260-7085)

1772: The History and Present State of Discoveries relating to Vision, Light, and Colours, by Joseph Priestley, Vol. 1; Vol. 2. (OCLC 14333937) [many references to Michell’s thinking] 

1783: On the Means of discovering the Distance, Magnitude, &c. of the Fixed Stars, in consequence of the Diminution of the Velocity of their Light, in case such a Diminution should be found to take place in any of them, and such other Data should be procured from Observations, as would be farther necessary for that Purpose, by John Michell, in Phil. Trans. R. Soc. Lond. 1784 Vol. 74 pp. 35–​57; (ISSN 0261-0523)
1784: On the Means of discovering the Distance, Magnitude, &c. of the Fixed Stars, in consequence of the Diminution of the Velocity of their Light, in case such a Diminution should be found to take place in any of them, and such other Data should be procured from Observations, as would be farther necessary for that Purpose, by John Michell. (OCLC 562762689)

1785: Correspondence, by John Michell, in The Monthly Review, Vol. 72, 1785 June, pp. 478–​480. (OCLC 656868867) [claim of priority over Canton] 

1798: Experiments to determine the Density of the Earth, by Henry Cavendish, in Phil. Trans. R. Soc. Lond. 1798 Vol. 88 pp. 469–​526. (ISSN 0261-0523)

1810: Copy of a List of the principal British Strata, by the late Rev. John Michel, by John Farey, Senior, in Philosophical Magazine, Vol. 36, No. 148, 1810 August, pp. 102–​105. (ISSN 1478-6435, eISSN 1478-6443)

1818: The Geology of England, by William Henry Fitton, in The Edinburgh Review, Vol. 29, No. 58, 1818 February, pp. 311–​337 (ISSN 1751-8482) [Michell at pp. 318-9. See also 1832] 

1818: On the very correct Notions concerning the Structure of the Earth, entertained by the Rev. John Michell, as early as the Year 1760; and the great Neglect which his Publication of the same has received from later Writers on Geology …, by John Farey, Senior, in Philosophical Magazine, Vol. 52, issue 245, 1818 September, pp. 183–​195; (ISSN 1478-6435, eISSN 1478-6443)
1818: ditto continued part 2, ibid., issue 246, 1818 October, pp. 254–​270;
1818: ditto continued part 3, ibid., issue 247, 1818 November, pp. 323–​341.

1832: Notes on the History of English Geology, by William Henry Fitton, in Philosophical Magazine, Ser. 3, Vol. 1, No. 4, 1832 October, pp. 268–​271. (ISSN 1478-6435, eISSN 1478-6443) [Revised from 1818] 

1850: On the alleged evidence for a Physical Connexion between Stars forming Binary or Multiple Groups, deduced from the Doctrine of Chances, by James David Forbes, in Philosophical Magazine, Ser. 3, Vol. 37, No. 252, 1850 December, pp. 401-427. (ISSN 1478-6435, eISSN 1478-6443)

1871: Sir William Herschel, by Khoda Bux^{[Andrew Thomas Turton Peterson]}, in English Mechanic and World of Science, Vol. 13, No. 325, 1871 June 16, pp. 309–​10. (OCLC 265486906) [infos on Michell, some true, some false: see Hutton 2006] 

1883: Michell, John, in Encyclopædia Britannica, 9th ed., Vol. 16, p. 237.

1890: The Life and Letters of the Reverend Adam Sedgwick, by John Willis Clark and Thomas McKenny Hughes, Vol. 1, pp. 191–​2. (OCLC 2684225) [source of a frequently quoted erroneous date for Michell’s death] 

1892: The Rev. John Michell, Astronomer and Geologist, by John Richard Sutton (1865–​1937), in Knowledge : an Illustrated Magazine of Science, Vol. XV (n.s. vol. VII), No. 84, 1892 October, pp. 188–​191; (OCLC 1715125) [earliest found biography of Michell] 
1892: ditto continued part 2, ibid., No. 85, 1892 November, pp. 206–​208.

1894: Michell, John, by Agnes Mary Clerke, in Dictionary of National Biography, Vol. 37, pp. 333–​4. [many falsehoods copied from Khoda Bux 1871] 

1907: Michell’s astronomical views, in Astronomical Essays : historical and descriptive, by John Ellard Gore, pp. 112–​123. (OCLC 3008788)

1911: Michell, John, in Encyclopædia Britannica, 11th ed., Vol. 18, pp. 370–​1.

1918: Memoir of John Michell, Fellow of Queens’ College 1749, by Sir Archibald Geikie. (OCLC 1869340)

1921: Founders of Seismology.—I. John Michell, by Charles Davison, in Geological Magazine, Vol. 58, Issue 3, pp. 98–​107. (ISSN 0016-7568, eISSN 1469-5081)

1927: The Founders of Seismology, by Charles Davison, pp. 12–​24. (OCLC 2480997)

1964: Michell, John, in Asimov’s Biographical Encyclopedia of Science and Technology : the living stories of more than 1000 great scientists…, by Isaac Asimov, #136a, pp. 148–​9; (OCLC 523479)
1972: Michell, John, in Asimov’s Biographical Encyclopedia of Science and Technology : the lives and achievements of 1195 great scientists…, by Isaac Asimov, #249, p. 172; (OCLC 277910)
1982: Michell, John, in Asimov’s Biographical Encyclopedia of Science and Technology : the lives and achievements of 1510 great scientists…, by Isaac Asimov. (ISBN 978-0-385-17771-9)

1966: The Scientific Work of the Reverend John Michell, by Clyde Laurence Hardin, in Annals of Science, Vol. 22:1, pp. 27–​47. (ISSN 0003-3790, eISSN 1464-505X)

1968: John Michell and Henry Cavendish: Weighing the Stars, by Russell McCormmach, in The British Journal for the History of Science, Vol. 4 issue 2, pp. 126–​155. (ISSN 0007-0874, eISSN 1474-001X)

1974: Michell, John, by Zdeněk Kopal, in the Dictionary of Scientific Biography, vol. 9, pp. 370–​1; (ISBN 978-0-684-10120-0)
2008: Michell, John, by Zdeněk Kopal, in the Complete Dictionary of Scientific Biography, vol. 9, pp. 370–​1. (ISBN 978-0-684-80588-7, eISBN 978-0-684-31559-1)

1977: John Michell’s theory of matter and Joseph Priestley’s use of it, by John Schondelmayer Parry, M.Phil thesis, Imperial College London.

1978: Johann Georg von Soldner and the gravitational bending of light …, by Stanley L. Jaki, in Foundations of Physics, Vol. 8, issue 11–​12, December 1978, pp. 927–​950. (ISSN 0015-9018, eISSN 1572-9516) [see p. 936n15 for the earliest note of Michell’s dark stars in the context of modern black holes] 

1979: John Michell and Black Holes, by Simon Schaffer, in Journal for the History of Astronomy, Vol. 10:1, pp. 42–​43. (ISSN 0021-8286, eISSN 1753-8556) (Bibcode: 1979JHA....10...42S)

1979: The man who invented black holes : His work emerges out of the dark after two centuries, by Gary Gibbons, in New Scientist, Vol. 82, no. 1161, 1979 June 28, p. 1101. (ISSN 0262-4079)

1982: Astronomy and Probability : Forbes versus Michell on the Distribution of the Stars, by Barry Gower, in Annals of Science, Vol. 39:2, pp. 145–​160. (ISSN 0003-3790, eISSN 1464-505X)

1993: John Michell, M.A., B.D., F.R.S. 1724?–1793, by John Evan Baldwin,^[Fellow] in Queens’ College Record 2003, pp. 14–​15.

2000: La Distance des Etoiles au dix-huitième Siècle: L'Echelle des Magnitudes de John Michell, by Hélène Vignolles, in Archive for History of Exact Sciences, Vol. 55, No. 1, 2000 August, pp. 77–​101. (ISSN 0003-9519 eISSN 1432-0657)

2000: Michell, John (1724–93), in Encyclopedia of Astronomy and Astrophysics, by Paul Murdin, Vol. 2, p. 1729. (ISBN 978-0-333-75088-9)

2001: Case study: John Michell and black holes, in Cosmic Horizons : Astronomy at the Cutting Edge, eds. Steven Soter and Neil deGrasse Tyson. (ISBN 978-1-56584-602-9)

2003: Mystery at the Rectory: some light on John Michell, by Richard J.S. Crossley (1938–​2014), in Yorkshire Philosophical Society Annual Report 2003, pp. 61–​69

2005: John Michell – a mystery solved, by Madeline Cox (1948–​2015), in Society for the History of Astronomy Newsletter, Issue 8, September 2005, p. 16.

2006: The Reverend John Michell: A Letter from his Great-grandson, by Eric Hutton, in The Antiquarian Astronomer, No. 3, 2006 Dec, pp. 65–8. (ISSN 1740-3677)

2007: John Michell, The Pleiades, and Odds of 496,000 to 1, by David W. Hughes and Susan Cartwright, in Journal of Astronomical History and Heritage, 10(2), 93–​99. (ISSN 1440-2807)

2007: The Rev. John Michell BD, FRS (1724–​1793), by Chris A. Butlin. [for the unveiling of the blue plaque at Thornhill] 

2007: Michell, John, by Laurent Hodges, in The Biographical Encyclopedia of Astronomers, Vol.  2, pp. 778–​9; (ISBN 978-0-387-31022-0 eISBN 978-0-387-30400-7)
2009: ditto, (ISBN 978-0-387-35133-9)
2014: Michell, John, by Laurent Hodges, in The Biographical Encyclopedia of Astronomers, 2014 edition, Vol.  2. (ISBN 978-0-387-31022-0 eISBN 978-0-387-30400-7)

2008: Michell, John, by Agnes Mary Clerke, revised by Michael Hoskin, in Oxford Dictionary of National Biography. [several errors] 

2008: A Blue Plaque for a Queensman, in Queens’ College Record 2008, pp. 29–​31.

2009: Michell, Laplace and the Origin of the Black Hole Concept, by Colin Robert Lister Montgomery, Wayne Orchiston, & Ian Whittingham, in Journal of Astronomical History and Heritage, 12(2), 2009 July, pp. 90–​96. (ISSN 1440-2807)

2009: Schwarzschild Radius Before General Relativity: Why Does Michell-Laplace Argument Provide the Correct Answer?, by Giovanni Preti, in Foundations of Physics, Vol. 39, Issue 9, 2009 September, pp. 1046–​1054. (ISSN 0015-9018, eISSN 1572-9516)

2012: Weighing the World: The Reverend John Michell of Thornhill, by Russell McCormmach. (ISBN 978-94-007-2021-3, eISBN 978-94-007-2022-0)

2013: John Michell (1724-93): Father of Magnetometry?, by Jim Grozier.

2016: Michell, Laplace e as estrelas negras: uma abordagem para professores do Ensino Médio, by Rodrigo Rodrigues Machado & Alexandre Carlos Tort, in Revista Brasileira de Ensino de Física, Vol. 38 no. 2, pp. e2314-1–​e2314-8. (ISSN 1806-1117 eISSN 1806-9126)