Oeuvres complètes. Tome VII. Correspondance 1670-1675

N^o 2067.
R. Hooke.
1675¹⁾.
Appendice I au No. 2065.

Postscript.

I Should have here taken leave of my Reader for this time, but that finding in the Transactions²⁾ a passage inserted out of the French Journal de Scavans³⁾, about the invention of applying a Spring to the Ballance of a Watch for the regulating the motion thereof, without at all taking notice that this Invention was first found out by an English-man, and long since published to the World: I must beg the Readers patience, whilst I, in vindication of my own right against some unhandsome proceedings, do acquaint him with the state of this matter.

About seventeen years since, being very inquisitive about the regulating the measure of Time, in order to find the Longitude, I did from an Art of Invention, or mechanical Algebra⁴⁾ (which I was then Master of) find out and perfect this

1) La pièce qui suit forme le ‘Postcript’ de l'ouvrage cité dans la Lettre N^o. 2025, note 8.

2) Les Philosophical Transactions N^o. 112, du 25 mars 1675 [V. st.]. Consultez la Lettre N^o. 2013, note 8.

3) La pièce N^o. 2014.

4) Hooke, dans la préface de sa ‘Micrographia’, parle d'une certaine méthode, dont il a le secret, pour résoudre des problémes de mécanique, en disant: ‘Indeed it is possible to do as much by this method in Mechanicks, as by Algebra can be perform'd in Geometry.’ Consultez les Lettres N^os. 1331 et 1338.

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contrivance, both as to the Theory and Experimental verification thereof, of which I then discoursed to divers of my Friends but concealed the modus.

About fifteen years since, to wit, in the year 1660, presently after his Majesties happy Restauration, I was in treaty with several Persons of Honour⁵⁾ (some of which are yet living, though one of them is since dead⁶⁾, but I have sufficient evidence to produce in his own writing that he was one) for the discovery thereof, upon proposed Articles of encouragement. This I can prove by undeniable Witnesses yet living and I have still all the Papers, Articles, and Transactions of this matter by me, in their own hand-writing.

In order to bring this Treaty to pass, I was necessitated to discover something of [my] Invention about measuring Time, which was, this way of applying Springs to the arbor of the Ballance of a Watch, for the regulating the vibrations thereof in all postures. And this I did, to the end that I might gain somewhat of belief in those Noble Persons (with whom I was to treat) That I had somewhat more than ordinary, and was not one of the heard-of Pretenders to that Invention: which effect it had, and their Treaty with he had finally been concluded for several Thousand pounds, had not the inserting one Clause broke it off, which was, That if after I had discovered my Inventions about the finding the Longitude by Watches, or otherwise (though in themselves sufficient) They, or any other Person should find a way of improving my Principles, he or they should have the benefit thereof, during the terms of the Patent, and not I. To which Clause I could no waies agree, knowing 't was easie to vary my Principles a hundred waies, and 'twas not improbable but that there might be made some addition of conveniency to what I should at first discover, it being facile Inventis addere⁷⁾. And judging it most unreasonable to be deprived of the benefit os my Inventions, in

5) Lord Brouncker, Robert Boyle et Sir Robert Moray. Voir l'écrit, cité dans la Lettre N^o. 2076, note 1, dans lequel Hooke, parlant de sa montre à ressort, dit: ‘one of which kind I shewed to the right Honourable the Lord Viscount Brouncker the Honourable Robert Boyle Esq: and Sir Robert Moray in the year 1660 in order to have gotten Letters Patent for the use and benefit thereof.’ On peut comparer encore, avec le récit qui va suivre, celui de Moray, dans la Lettre N^o. 1481, sur les mêmes négociations. Il résulte de ce dernier récit que ce ne fut qu'en 1664 que Hooke confia son secret à Brouncker et Moray.

6) Sir Robert Moray; voir la pièce N^o. 2010, note 7.

7) Comparez de Hautefeuille, à la fin de la pièce N^o. 2028. Hooke imite encore de Hautefeuille, lorsque, sur le titre de son traité des Hélioscopes, il cite en abrégé les deux vers de Vergilius: Hos ego versiculos feci, tulit alter honores, Sic vos non vobis nidificatis aves, etc. Voir la Lettre N^o. 2025, note 8, et la pièce N^o. 2024, note 9.

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themselves sufficient, because others might vary them, or any other ways improve them, of which it was very probable they would have no thought, if they had not the advantage of being instructed by my discovery, it having lain hid some thousands of years already, as indeed the effect hath made evident and certain, there having been nothing done by any body else upon that matter for these fifteen years.

Upon this point our Treaty was broken off, and I concealed the farther discovery of the other more considerable parts of my Inventions, for the regulating of Time-Keepers, as hoping I might find some better opportunity of publishing them together with my way of finding the Longitudes of Places, for which I hoped to have had some benefit for all the labour, study, and charge I had been at for the perfecting thereof. Upon this I was told, That I had better have then discovered all, since there were others that would find it out within six months, to which I answered, that I would try them one seven years; and it is now about twice seven, and I do not find it yet found out. Indeed Mr. Hugens hath made use of that part I discovered, and somewhat Mr. Leibnitz⁸⁾ hath hit upon, but both of them are imperfect as I shall hereafter shew⁹⁾.

'T is true, I was alarum'd by one of those Persons about two years after that, who told me, That he had news that the Longitude was found out by a Person of Honour¹⁰⁾, by a way of carrying Mr. Hugens's Pendulum-Clock, at Sea, by the help of a Ball and Socket, hung to the underside of the Deck of a Ship. But having a description of it, I presently told that Person, That that invention would do mine no harm; and indeed we experimentally found it useless to that effect not long after, upon a trial made of carrying the said Clocks off to Sea in one of His Majesties Pleasure-Boats, in the year 1662.

The invention indeed in it self was ingenious, and did much more than what Mr. Hugens did expect, as I was then informed by the Right Honourable the Earl of Kincardine¹¹⁾ the Author and perfecter of that part of the Invention. But wanting a little addition (which I concealed, and Mr. Hugens hath not got yet that I hear of) it failed of the effect that was expected. Notwitstanding this, it was not long after published in Low Dutch¹²⁾, and presently after in

8) Consultez la Lettre N^o. 2031, note 2.

9) Des deux mécanismes, celui de Hooke et celui de Huygens, le premier est resté inconnu jusqu'aujourdhui, le second forme, de nos jours encore, le principe des montres et des chronomètres.

10) Robert Bruce, depuis Earl of Kincardin.

11) Consultez, sur les relations de Chr. Huygens et Bruce, la Lettre N^o. 1954, note 8. L'idée de suspendre l'horloge à pendule, de manière qu'elle puisse osciller sur son support, était bien de Huygens. Voir la Lettre N^o. 986.

12) L'écrit ‘Het Onderwijs’; voir la Lettre N^o. 1290, note 8.

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English¹³⁾; wherein what made for it was related, but what made against it was concealed, though they were both equally known.

But on the otherside, all that I could obtain was a Catalogue of Difficulties, first, in the doing of it, secondly in the bringing it into publick use, thirdly, in making advantage of it. Difficulties were propounded from the alteration of Climates, Airs, heats and colds, temperature of Springs, the nature of Vibrations, the wearing of Materials, the motion of the Ship, and divers others. Next it would be difficult to bring it to use, for Sea-men knew their way already to any Port, and Men would not be at the unnecessary charge of the Apparatus, and observations of the Time could not be well made at Sea, and they would no where be of use but in East and West India Voyages, which were so perfectly understood that every Common Sea-man almost knew how to Pilot a Ship thither. And as for making benefit, all People lost by such undertakings; much had been talkt about the Praemiums for the Longitude, but there was never any such thing, no King or State would ever give a farthing for it, and the like; All which I let pass.

At the earnest importunity of a Dear Friend of mine, since deceased, I did, in the year 1664, read several of my first Cutlerian Lectures upon that Subject, in the open Hall at Gresham Colledge, at which were present, besides a great number of the Royal Society, many Strangers unknown to me, I there shewed the ground and reason of that application of Springs to the Ballance of a Watch, for regulating its motion, and explained briefly the true nature and principle of Springs, to shew the Physical and Geometrical ground of them. And I explained above twenty several ways by which Springs might be applied to do the same thing and how the Vibrations might be so regulated, as to make their Durations either all equal, or the greater slower or quicker than the less, and that in any proportion assigned. Some of these ways were applicable to lesser Vibrations, others to greater, as of 2, 3, 4, 5, 6. or what number of Revolutions were desired; the models of which I there produced, and I did at the same time shew wherein the aforesaid Sea-Clocks were defective.

All these particulars also were at several other times, at the Publick meetings of the Royal Society, discoursed, experimented, and several Models produced. I did also, at the earnest desire of some Friends, in the year 1664 and 1665, cause some of the said Watches to be made, though I was unwilling to add any of the application of the Spring to them, as waiting a better opportunity for my advantage.

Of all these things the Publisher of the Transactions was not ignorant, and I doubt not but Mr. Hugens hath had an account, at least he might have read of it in the History of the Royal Society as was enough to have given him notice of it,

13) Voir la Lettre N^o. 1301, note 18.

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for page 247 of that History¹⁴⁾ amongst other Experimented Inventions, there are recounted several new ways of Pendulum Watches for the Pocket, wherein the motion is regulated by Springs, &c. The account of the several ways was given somewhat larger to the Learned Author of that excellent History, though he, as judging it more proper to his design, was pleased to give only this summary account. Mr. Hugens might therefore, if he had pleased, have mentioned the first Inventer, Nam ingenuum est fateri; as he might also that of the Circular Pendulum, which is mentioned in the Same page¹⁵⁾ of the aforesaid History.

But though he would not please to confess he knew may published Invention, yet I am sure he hath manifested, that he knows no more then what I had formerly discovered, he having not in [the] least mentioned the other Contrivance, which is the principal, and without which the first part of the Invention is but lame and imperfect, and doth but limp on one leg, and will some time hobble, and stumble and stand still. And the said Watches will not be tres-Juste¹⁶⁾ nor shew

14) L'ouvrage dont la deuxième édition a été citée dans la Lettre N^o. 1114, note 4. Le titre de la première est le suivant:
The History of the Royal-Society, For the Improving of Natural knowledge By Tho. Sprat. London, Printed by T.R. for F. Martyn at the Bell without Temple-bar, and J. Allestry at the Rose and Crown in Duck-lane, Printers to the Royal Society. mdclxvii. in-4^o.
L'énumération des instruments inventés par les membres de la Société renferme, à la page 247, la mention suivante: ‘Several new kinds of Pendulum Watches for the Pocket, wherein the motion is regulated, by Springs, or Weights, or Loadstones, or Flies moving very exactly regular.’
Dans ce livre, Sprat passe en revue les relations de la Société royale avec d'autres pays. Arrivé aux Pays-Bas, il dit, page 127: ‘In the Low Countries, their Interest, and Reputation (c'est-à-dire celles de la Société royale), has been establish'd, by the Friendship of some of their cheaf Learned men, and principally of Hugenius. This Gentleman has bestow'd his pains, on many parts of the speculative and practical Mathematicks, with wonderfull successes. And particularly his applying the Motion of Pendulum: to Clocks, and Watches, was an excellent Invention. For thereby there may be a means found out, of bringing the measures of Time to an exact Regulation, of which the benefits are infinite. In the prosecution of such Discoveries, he has often requir'd the aid of this Society; he has receiv'd the light of their Trials, and a confirmation of his own, and has freely admitted their alterations, or amendments. And this learned correspondence with him, and many others, is still continued, even at this present time, in the breach between our Countries: Their Great Founder [Charles II], and Patron still permitting them to maintain the Traffick of Sciences, when all other Commerce is intercepted.’

15) Dans les termes suivants: ‘A new kind of Pendulum Clock, wherein the Pendulum moves circularly, going with the most simple, and natural motion, moving very equally, and making no kind of noice.’
On remarquera que Sprat n'entre dans aucun détail et s'est même abstenu de citer le nom de Hooke. Consultez la Lettre N^o. 2010, note 4.

16) Allusion à l'exorde de l'article de Huygens dans le Journal des Sçavants, la pièce N^o. 2014.

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the Longitude at Sea or Land, but, on the contrary, they will be subject to most Inequalities of motion and carriage, and with many of those motions will be apt to stand still, whatever to the contrary is affirmed in the French Journal or in the English Transactions.

I forbear now to mention any further the carriage of the Writer¹⁷⁾ of the Transactions in this Affair, and begging my Readers excuse for this digression, I shall conclude this Tract with a short communication of the general ground of my Invention for Pocket-Watches, the number of particular ways being very great, which (that the true Lovers of Art, and they only may have the benefit of it) I have set down in the Universal and Real Character of the late Reverend Prelate, my Honoured Friend Dr. John Wilkins¹⁸⁾, Lord Bishop of Chester, deceased. In which I could wish, that all things of this nature were communicated, it being a Character and Language so truly Philosophical, and so perfectly and thoroughly Methodical, that there seemeth to be nothing wanting to have the utmost perfection, and highest Idea of any Character or Language imaginable, as well for Philosophical as for common and constant use. And I have this further to desire of my Reader, who will be at the pains to decipher and understand this description, that he would only make use of it for his own information, and not communicate the explication thereof to any that hath not had the same curiosity with him self¹⁹⁾.

17) H. Oldenburg.

18) Il a été question de cette langue universelle dans les Lettres Nos. 1721 et 1730. L'ouvrage dans lequel Wilkins expose son système se trouve décrit dans la note 9 de la Lettre N^o. 1721. Il forme un in-folio de 454 pages, suivi d'un dictionnaire alphabétique de 170 pages. Le système suivi par Wilkins revient à diviser toutes les notions, qu'il s'agit d'exprimer par écrit, en 40 genres, représentés graphiquement chacun par un signe particulier, consistant en un trait horizontal modifié de diverses manières par l'adjonction de traits verticaux, de cercles ou de crochets au milieu. Des appendices, appliqués de diverses façons à l'extrémité de gauche, permettent de distinguer jusqu'à dix différences de chacun de ces genres; un nombre égal de signes appliqués à l'extrémité droite sert à indiquer dix espèces de chaque différence. On arrive ainsi à un maximum de 4000 notions. On a encore un signe, un simple rond, pour distinguer deux notions correlatives qui, dans la Table systématique, sont indiquées soit comme opposées, soit comme semblables. Il y a encore d'autres signes pour exprimer qu'une notion est employée passivement, adjectivement, etc. Il est clair que le déchiffrement de quelque phrase, écrite dans cette langue, est compliqué et très difficile et laisse toujours quelque ambiguïté, de sorte que, lorsqu'il s'agit de la description exacte et précise d'un instrument ou d'un mécanisme, le langage universel doit nécessairement rester en défaut.

19) Le secret, en effet, a été bien gardé. On n'a jamais publié en quoi a consisté le mécanisme de Hooke. Ainsi Hooke lui-même, en s'abstenant de le faire connaître, a, de fait, renoncé aux droits d'un inventeur.
Il est, en tout cas, inadmissible qu'il se serait servi d'un ressort en spirale. En effet, s'il en eût été ainsi, rien ne l'aurait empêché d'invoquer le témoignage de Lord Brouncker et de Robert Boyle, auxquels il avait confié, en 1664, son secret. De plus, Waller, le successeur de Hooke dans la charge de secrétaire de la Société Royale, et qui a eu entre les mains les papiers de Hooke, n'y a rien trouvé, qui indiquerait que celui-ci se soit servi du ressort en spirale. Consultez l'ouvrage:
The Posthumous works of Robert Hooke m.d.s.r.s. Geom. Prof. Gresh. &c. Containing his Cutlerian Lectures, and other Discourses, Read at the Meetings of the Illustrious Royal Society. In which I. The present Deficiency of Natural Philosophy is discoursed of, with the Methods of rendering it more certain and beneficial. II. The Nature, Motion and Effects of Light are treated of, particularly that of the Sun and Comets. III. An Hypothetical Explication of Memory; how the Organs made use of by the Mind in its Operation may be mechanically understood. IV. An Hypothesis and Explication of the Cause of Gravity, or Gravitation, Magnetism, &c. V. Discourses of Earthquakes, their Causes and Effects, and Histories of several; to which are annext, Physical Explications of several of the Fables in Ovid's Metamorphoses, very different from other Mythologick Interpreters. VI. Lectures for improving Navigation and Astronomy, with the Descriptions of several new and usefull Instruments and Contrivances the whole full of curious Dispositions and Experiments. Illustrated with Sculptures. To these Discourses is prefixt the Author's Life, giving an Account of his Studies and Employments, with an Enumeration of the many Experiments, Instruments, Contrivances and Inventions, by him made and produc'd as Curator of Experiments to the Royal Society. Publish'd by Richard Waller, R. S. Secr. London: Printed by Sam. Smith and Benj. Walford (Printers to the Royal Society) at the Princes Arms in St. Paul's Church-Yard. 1705, in-f^o.
Dans la Vie de Hooke, qui précède cet ouvrage, Waller rend compte de ce qu'il a trouvé par rapport aux droits de Hooke sur l'invention des montres à ressort en spirale, mais il ne peut produire aucun document où il est question d'un tel ressort dans les montres de Hooke. Waller doit se borner à des conjectures, qui se trouvent démenties par les témoignages de notre Correspondance. Il dit entre autres:
‘Now tho' this does not mention the Springs being spiral or fastened to the Arbor of the Ballance, yet it appears it was so by what is related above and a Passage I have seen in a Letter from Sir Robert Moray to Mr. Oldenburgh, dated Oxon Sept. 30. 1665. clears it, in which are these words. “You (meaning Oldenburgh) will be the first that knows when his (that is Hugyen's) Watches will be ready, and I will therefore expect from you an account of them, and if he imparts to you what he does, let me know it; to that purpose you may ask him if he doth not apply a Spring to the Arbor of the Ballance, and that will give occasion to say somewhat to you; if it be that, you may tell him what Hooke has done in that matter, and what he intends more.” Altho' I cannot be assur'd what Oldenburgh wrote to Monsieur Huygens, yet it is probable their intimacy procur'd what he knew (consultez la Lettre N^o. 2066, note 7); and it is evident that Huygen's discovery of this was first publish'd in the Journal des Scavants, and from thence in the Philos. Transact. for March 25th. 1675, about ten Years after that Letter of Sir Morray, and near fifteen after Hooke's discovery of it.’
Dans ce passage également, il n'est nullement question de ressorts en spirale. Quant à ce qui regarde la lettre citée de Moray à Oldenburg, la demande de Moray est évidemment la suite de ce que Huygens lui avait écrit le 18 septembre précédent dans la Lettre N^o. 1466, au sujet des projets du duc de Roannes et de Pascal, datant de 1660, lettre où Huygens ajoute qu'il possédait des manières ‘beaucoup meilleures.’ Oldenburg, dans sa lettre du 7 octobre [V. st.], le N^o, 1479, tout en parlant des montres de Hooke, ne s'est pas acquitté de la commission de Moray.
La question, d'ailleurs, se trouve complètement tranchée par les déclarations de Brouncker. Consultez la Lettre N^o. 2073.
Waller termine cette partie de la Vie de Hooke en disant: ‘But this I suppose may be au undoubted Truth, the Spiral Springs were not apply'd generally to regulate Watches 'till after the Dispute with Huygens. Cette assertion, toutefois, ne peut s'appliquer qu'à l'Angleterre. La Correspondance de Huygens prouve que les montres de Huygens se répandirent à Paris aussitôt après l'invention, quelques mois avant la querelle suscitée par Hooke.

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This I do, not so much to hinder the spreading of this Description here delivered, as to revive, and, if possible, bring into use and practice that excellent Designe:

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It being a Character and Language perfecty free from all manner of ambiguity, and yet the most copious, expressive and significative of any thing or Notion

Tabula III.

imaginable, and, which recommends it most to common use, the most easie to be understood and learnt in the World. See Table the third²⁰⁾.

20) Le hasard nous a fait rencontrer une solution, dont, cependant, nous ne pouvons garantir l'exactitude. Dans un exemplaire de la collection des ouvrages de Hooke, (voir la Lettre N^o. 1363, note 6) que nous avons pu acquérir à la vente de la bibliothèque de M. Bierens de Haan, J^o. Weldens, le premier détenteur, qui paraît avoir étudié le livre avec attention, a inscrit sur la Tabula III, ce qui suit:
‘The character underwritten deciphered. The contrivance of making exact pocket watches, is comprised in regulating them by two ways:
The first is, by giving a resistance to all the bowing or bent (i.e. y^e force of y^e Spring) & motion, soe as the power of Gravity (which Mr. Hooke calls y^e Attractive power of the Earth) acting, neither posture nor curved motion nor uneven inside of the small case of ye Watch can cause any Irregularity. The second is. The natural Acting of the Moderators within ye Watch soe as noe naturall power acting irregularly upon the Springs or forcing of the Wheeles, or any other of the Watch, can disturbe the motion.
The First is done by ye motion of Ballances, moving constantly contrary, the first to the second.
The other is done by Springs, or some other naturall forces acting upon the ballances or rulers of the motion.’
La traduction en langage ordinaire est à peine plus intelligible que, pour un profane, l'hiéroglyphe même par lequel Hooke, à ce qu'il dit, a voulu atteindre les deux buts difficilement conciliables: celui de cacher sa pensée et celui de faire voir combien le langage universel de Wilkins est propre à exprimer sa pensée sans ambiguïté. Il en résulte, toutefois, que la soi-disant explication de Hooke ne contient que des généralités; elle ne précise rien quant au mécanisme employé à appliquer ses principes, et il est certain qu'il n'y est nullement question de l'unique solution qui a réussi jusqu'ici, savoir le ressort en spirale de Huygens.

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To fill the vacancy of the ensuing page, I have here added a decimate of the centesime of the Inventions I intend to publish, though possibly not in the same order, but as I can get opportunity and leasure; most of which, I hope, will be as useful to Mankind, as they are yet unknown and new.

1. A way of Regulating all sorts of Watches or Time-keepers, so as to make any way²¹⁾ to equalize, if not exceed the Pendulum-Clocks now used²²⁾.

2. The true Mathematical and Mechanical form of all manner of Arches for Building, with the true butment necessary to each of them. A Problem no Architectonick writer hath even yet attempted, much less performed, abcccddeeeee f gg iiiiiiii ll²³⁾ mmmm nnnnn oo p rr sss ttttttt uuuuuuuu x.

3. The true Theory of Elasticity or Springiness, and a particular Explication thereof in several Subjects in which it is to be found: And the way of computing the velocity of Bodies moved by them. ceiiinosssttuu²⁴⁾.

21) On a corrigé en marge: watch.

22) C'est probablement le mécanisme indiqué à la page 43 du ‘Lampas’, l'écrit cité dans la pièce N^o. 2076, note 1. Sous le titre: ‘A New Principle for Watches’, Hooke y fait mention d'un mouvement d'horlogerie continu, balancé par la résistance qu'éprouvent des ailettes, dont l'écartement est réglé par un ‘Spiral Spring’, dénomination qui, dans ce cas évidemment, indique un ressort à boudin.

23) Le deuxième la été biffé dans l'exemplaire de la Royal Astronomical Society, ce qui nous semble prouver que l'exemplaire a été corrigé par l'auteur lui-même, puisque le secret de l'anagramme est resté caché. Voir la Lettre N^o. 1989, note 1.

24) La solution se trouve dans le Traité:
Lectures De potentia Restitutiva, or of Spring Explaining the Power of Springing Bodies. To which are added some Collections Viz. A. Description of Dr. Pappins Wind-Fountain and Force-Pump. Mr. Young's Observation concerning natural Fountains. Some other Considerations concerning that Subject. Captain Sturmy's remarks of a Subterranean Cave and Cistern. Mr. G.T. Observations made on the Pike of Teneriff, 1674. Some Reflections and Conjectures occasioned thereupon. A Relation of a late Eruption in the Isle of Palma. By Robert Hooke. S.R.S. London, Printed for John Martyn, Printer to the Royal Society, at the Bell in St. Pauls Church-Yard 1678. in-4^o.
Cet écrit est le sixième et dernier de la Collection citée dans les Lettres N^os. 2025, note 8, 2000, note 3, 1989, note 1 et 1363, note 6.
On y lit: "Ut tensio sic vis. That is, The Power of any Spring is in the same proportion with the Tension thereof." Il résulte de ce que l'auteur fait suivre, qu'il veut exprimer la proportionalité de la grandeur de la déformation avec la force.

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4. A very plain and practical way of counterpoising Liquors, of great use in Hydraulicks. Discovered.

5. A new sort of Object-Glasses for Telescopes and Microscopes, much outdoing any yet used. Discovered.

6. A new Selenoscope, easie enough to be made and used, whereby the smallest inequality of the Moons surface and limb may be most plainly distinguished. Discovered.

7. A new sort of Horizontal-Sayls for a Mill, performing the most that any Horizontal-Sayls of that bigness are capable of; and the various use of that principle on divers other occasions. Discovered.

8. A new way of a Post-Charriot for travelling far, without much wearying Horse or Rider. Discovered.

9. A new sort of Philosophical-Scales, of great use in Experimental Philosophy. cdeiinnoopsssttuu²⁵⁾.

10. A new Invention in Mechanicks of prodigious use, exceeding the chimera's of perpetual motions for several uses. aaaaebccddeeeeeegiiilmmmnn ooppqrrrrstttuuuuu.

aaeffhiiiilnrrsstuu.

25) En marge de l'exemplaire de la Royal Astronomical Society se trouve écrit: ‘See page the 5th of the 6th Lecture.’ Ce serait donc une échelle de déformation élastique, probablement employée comme dynamomètre.