NOVEMBEB 1, 1892.] 



KNOWLEDGE, 



207 



(the j'ear after Michell got his fellowship), chiefly, it would 

 seem, in recognition of his wealth and prospects. It is a 

 curious exemplitication of the tenacity with which feudal 

 instincts clung to the University in those comparatively 

 recent days, that whereas " Phdip, Duke of Newcastle, 

 John, Earl of Sandwich, and George SavUe, Esquire,'' 

 i/nictd all the public ceremonies of the University, the 

 " Masters and Fellows in their robes " merely uttendLd. 



Mr. Ansted, who, by the way, knew more than most 

 people about Michell, remarks that Michell " appears to 

 have discontinued scienlitic pursuits on succeeding to the 

 living ; at all events,' he adds, '■ nothing more was made 

 public by him during the remainder of his life.'"' This is 

 quite wrong, though, seventeen years afterwards, namely, 

 in 1784, Michell published in the Philosophical Tranti- 

 actions an ably- reasoned article " on the means of discover- 

 ing the distance, magnitude, &c., of the fixed stars, in 

 consequence of the diminution in velocity of their light, in 

 case such a diminution should be found to take place in 

 any of them, .Itc.'' This discussion exhibits Michell's 

 marvellous talents unimpaired ; but it wUl not be necessary 

 to consider it here, for it was founded on Newton's 

 erroneous corpuscular theory of Light, then generally 

 accepted. Had that theory been tenable, Michell's subtle 

 suggestions might have been appUed with success in 

 the course of time. As it was, when the corpuscles 

 had succumbed to Young's vigorous assault, a modification 

 of Michell's plans was adopted to find the velocities with 

 which some of the stars are moving from or towards the 

 earth, albeit nothing is learned in. this way of then- distances. 

 One result worked out in this paper of 1784 is too 

 pretty to be passed over. If, said he, light be sent out in 

 the form of material particles from luminous bodies (as 

 Newton supposed), these particles must be amenable to 

 gravity, hence their original velocities would be consider- 

 ably modified by the retarding action of the emitting 

 bodies ; and in cases where these last were large enough, 

 the corpuscles would be forced to return to their starling 

 places. The consequence would be that the larger stellar 

 masses wovild be totally invisible. Advanced knowledge 

 has taught us that this result is not in accordance with 

 facts, and that the mass of the luminous body can have no 

 eftect on the velocity of the light it sends forth. Yet 

 arriving, strangely enough, at some truth fi'om erroneous 

 premises, Michell managed to deduce the result, whose 

 observational proof was not forthcoming for the best part 

 of the following century, that by the motions of some 

 of the bright stars we might be able to detect the 

 existence of dark companions to them ; and this, when 

 astronomers as yet did not recognize the existence even of 

 lucid binary systems. 



In the seclusion of Thornhill, Michell thought out and 

 (onstructed the celebrated torsion balance for weighing 

 the earth. Doubtless it was the outcome of his magnetic 

 experiments, not that he confounded magnetism with 

 gravitation. It is still the best instrument we have for 

 the purpose, and the measm-e of the earth's density 

 obtained by this very instrument (somewhat modified, it is 

 true, in minor details) gave the first measme of the 

 earth's density. An explanation of the machine would be 

 out of place here, but a complete account will be foimd in 

 the Philosophical Transactions for 1789 hy Michell's friend 

 Henry Cavendish, who first used it, MicheU having died 

 too soon to use it himself.f There is also a simple 



* Cambridge Portfolio 



+ Michell and Cavendish were great friends, and made geological 

 excursions together. Their acquaintance was, perhaps, first made at 

 Cambridge. Cavendish entered at Peterhouse on November 24th, 

 1749, but left without tiikiug a degree. 



accoimt in Y'oung's General Astronomy, and by the late 

 [ Mr. Proctor in the early part of the tHd and Xen- Astronomi/. 

 Archimedes is reported to have said that, given a lever 

 long enough, he would move the earth. Of Michell we 

 may say that he showed how to put the eaith in the 

 balance and weigh it. In this, as in other things. Michell 

 has been undervalued. He seldom gets the credit for bis 

 invention ; more frequently than not it is stated that 

 Cavendish himself designed the machine. Fortimately, 

 Cavendish's own declaration to the Royal Society is 

 expheit enough : " Many years ago," he says, " the 

 late Eev. John Michell, of this Society, contrived 

 a method of determining the density of the earth, 

 by rendering sensible the attractions of small 

 quantities of matter ; but as he was engaged in other 

 piu-suits, he did not complete the apparatus till a short 

 time before his death, and did not live to make any experi- 

 ments with it. After his death the apparatus came to the 

 Rev. Francis John Hyde Wollaston, Jacksonian Professor 

 at Cambridge, who, not having convenience for making 

 experiments wth it in the manner he could wish, was so 

 good as to give it to me. " Nothing could possibly be 

 clearer, and it may well seem surprising, in the face of such 

 a statement, that misapprehension should afterwards arise. 

 That it did arise is probably due to Lord Brougham, 

 whose article on Cavendish was widely read.* Un- 

 fortimately, the well-merited drubbing he got from the 

 (Jiiarterli/ lU'cieici was not taken to heart by later writers 

 as it should have been. Lord Brougham admitted subse- 

 quently that he had not so much as seen Cavendish's 

 paper on the torsion balance before publishing his senti- 

 ments concerning it. But whereas many persons read the 

 article wherein the invention of the torsion balance is 

 assigned in large type to Cavendish, it is to be feared that 

 few read the recantation in small type in an obscure corner 

 of a later volume. 



After a hfe of quiet usefulness, which wiU be more and 

 more appreciated as time goes on, Michell passed away on 

 the 21st of April, 1793. He was bm-ied in the south 

 chancel of St. Michael's, Thornhill. A flat plain stone 

 marks the spot, and another by its side is in memory of 

 his wife. The inscriptions are in plain capitals : — 



(1) " Rev. John Michell, 

 Died the 21st -April, 1793, 

 Aged 68 Yeabs." 



(2) " Axne Michell, 

 Relict of the Rev. John Michell, 

 Died the 3ed Novejtber, 1818, 

 Aged 86. " 



A nobly-worded but curiously punctuated tablet hangs 

 in the church to Michell's memory, and to that of his 

 brother. It runs thus : — 



•' In the chancel of this church are deposited the remains 

 of the Revd. Jno. Michell, B.D., F.R.S., and 26 years 

 Rector of this parish. Eminently disting^shed as the 

 •Philosopher, the Scholar. He had a just claim to the 

 character of the good Christian. In the relative and social 

 duties of Life ; the tender Husband, the indulgent Parent 

 the afl'ectionate brother and the sincere 1 riend were the 

 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 prmciple, 

 not form. As he hved in the possession of the esteem of 

 his parishioners, so he has carried to the grave their 

 regret. 



X See Jleii of Letters and Hcieace of the time of George III. 

 § Quar. Rec, Vol. LXXVII., ^a*.»im. 



