N^o 2075.
H. Oldenburg.
octobre 1675.
Appendice I au No. 2074.

La pièce a été imprimée par Oldenburg dans les Philosophical Transactions1).

II. A Description of Helioscopes and some other Instruments, made by Robert Hook, Fellow of the R. Society: London, printed for John Martyn, at the Bell in St. Paul's Churchyard. 1675. in 4^o.

Touching the Contents of this Book, as far as they relate to the Instruments therein described, I need say nothing here; I shall only touch upon some sorts of Passages in the Postscript of it, in which I find one of these our Tracts concerned. The said Postscript then takes the Liberty of reflecting upon a Passage in Numb. 112^th of these Transactions, viz. about the Invention of applying a Spring to the Ballance of a Watch finding Fault with the same for not having taken Notice, that this Invention was first found out by an Englishman, and long since published to the World, and complaining thereupon of unhandsome Proceedings.

Now forasmuch as the former Part of this Accusation doth directly concern the Author of the Transactions, and the latter is so ambiguously worded, as that it may be referr'd to the said Author, as well as to the French Journal des Scavans, it was thought fit to acquaint the Impartial and Candid Reader with the plain Truth of this Matter.

'T is certain then, that the Describer of the Helioscope, some Years ago, caused to be actually made some Watches of this Kind, yet without publishing to the World a Description of it in Print, but it is as certain, that none of those Watches succeeded, nor that any thing was done since to mend the Invention, and to render it useful, that we know of until Monsieur Hugens, who is also a Member of the Royal Society, as well as he is of the Royal Academy at Paris, sent hither a Letter dated January 30. 1674/752), acquainting us with an Invention of his of very exact Pocket-Watches, the Nature and Contrivance of which he imparted to us

(as he is wont to do other Inventions of his) in an Anagram; which he soon after, in a Letter of Febr. 20. 1674/753) explained to us by a full Description; for which the R. Society thought fit to return him Thanks, yet so as to intimate to him, that Mr. Hook had some Years ago invented a Watch of the like Contrivance4).

Not long after this there came over in the Journal des Scavans a printed Description5) of M. Hugens's Invention, together with a Delineation of the Figure of the same, which the Author of the Transactions produced at the publick Meeting of the R. Society, where M. Hook not only saw it, but took a Copy of the Figure it self at the same Time, unwilling to let him, that presented it there, take it Home without permitting him first to copy it. Which done, Mr. Hugens's Explication of his own Way, together with the Figure thereof, was, at his Desire, and after the perusal of the Noble President of the R. Society, printed the 12^th of March 1674/75, in Numb. 112. of the Transactions; the Describer of the Helioscope well knowing, that it was designed to be published in one of those Tracts; who, if he had given to the Author of them the least Intimation, importing that he desired, Notice might be taken at the same Time of his Invention of the like Kind, it would have been certainly done, as hath been done upon other Occasions, witness several of the same Tracts, wherein divers Discoveries of this Accuser have been formerly both printed and vindicated from the Usurpations of others; though indeed it was not necessary it should there be done now, since the said Animadverser could speak for himself in Print as soon as he pleased, as having laudably made use of late of the Press for publishing himself his own Inventions.

This is the very Truth of the Matter, in which whether there be any Thing on the Part of the Publisher of the Transactions, that deserves that Name of unhandsome Proceedings, he very willingly leaves to all ingenious Readers to judge: Besides, it might justly be considered, that pregnant and inventive Heads, well versed in the Mathematicks and Mechanicks, and furnish'd with a genuine Method of Investigation, may, and not seldom do, fall upon the same Discoveries and Inventions about the same time, especially if their Minds have been long addicted to and engaged in the same Researches: Of which, if there be Occasion, several considerable Instances may be produced to verify the Assertion. One of which, and fit to be taken Notice at present, is that the Publisher of the Transactions did, not long since, shew to the Accuser that Way of Monsieur Leibnitz, concerning exact portable Watches, which was printed in Numb. 113. of these Tracts6), he did acknowledge, that though he had known that Way too, ever since A. 1660,

yet he never declared it to any Body, and therefore could not say, M. Leibnitz had taken it from him.

Thus I shall dismiss him, not doubting, but that all Candid Readers will blame him for the Expression he uses p. 30. of his said Post-script, which is, that he forbears now to mention any further the Carriage of the Writer of the Transactions in this Affair: And only adding, that if this Writer of Mechanick shall think fit to explain what he means by it, he will certainly meet with a full Answer, vindicating the Integrity of the Publisher in such a Manner, that all impartial and good Men shall be abundantly satisfied therewith

- Speque metuque procul.

Horat.7).