QUATRIÈME COMPLÉMENT X LA DIOPTRIQUE. I<568 — 1692. 835 



choroidem afficientem. ficut fonus non eft corpus fed motus aeris feu fucculllonem, 

 in aures agentem. 



Romeri obfervacionem de lucis celeritate refert, et a Flamiledio et Halleio 

 probari dicit '^). 



Ut bene centrentur lentes objeftivae aliqua adfert '■•} , fed meam rationem non 

 actingit. 



p. 232 '5^. de dirigendis telefcopijs in cîelum , nortram quoque Aftrofcopiam 

 compendiariam allegat, et a.° 1685 vidiiïe ait Hagae in horto nollro,qu£e effet 

 ratio inventi. The defervedly celebrated monf.'' Hugens, one of the chief mathe- 

 matick Luminairies of the prefent âge &c. '") Addit fe eodem tempore vidiffe 

 Machinam meam Planetariam , or moving Ephemeris '''} a machine that cannot 

 be fufficiently admired. 



p. 226. Hookij inventum refert parandis longis lentibus ex datisbrevioribusque 

 inter binos orbes vitreos alterum utrinque planum alterum planoconvexum inter- 

 pofita aqua vel alio liquore pellucido, conjungit, ut convexa fuperficies fit 



of Light , that do necessarily belong to a Body , are so many and évident , that they leave no 

 room for any farther donbt in tliis matter. I shall mention but a few. And first. by this 

 Àfeclion of being refracted , 'tis nianifest that Light in its passage through this and t'other 

 Diaphanous Body does find a diferent Résistance. .. . The second Property , that confirms 



Light to be a Body raoved or thrust forward , is, That it requires time to pass froin one 



place to another. . , . A third proof. . . . is, That it cannot by any Art or Contrivance what- 

 ever be increased or diminished\, that is to say , we cannot magnifie (for instance) the Light 

 of the Sun or a Candie , no more than we can magnifie a Cubick Inch of Gold, or make it 

 more than a Cubick Inch. . . ". 



'5) Après avoir mentionné la démonstration de Romer sur la vitesse finie delà lumière et la 

 remarque à ce sujet de Newton dans ses „Principia, Lib. I, Schol. Prop. 96", Molyneux fait 

 suivre (p. 199): „For a conformation of ail which I appeal to the Labours of the Ingénions 

 Mr. Flamsteed andMr. Ha/ley, to whom the Learned World is for ever obliged by their 

 Advancements of Astronomy". 



'*) Molyneux consacre à ce sujet les p. 2 1 8 — 222 du „Chap. IV. Of Mechanick-Dioptricks". 



•5)Lisez:„223". 



'*) Voici le passage en entier: „The deservedly Celebrated Mons. Hugens, one of the chief 

 Mathematick Luminaries of the présent Age, has publish'd a small Tract, Astroscopia Com- 

 pettdiaria, designed only for Describing his wayof Managing great Classes with very little 

 trouble, and without a Tube. This I am sure is no barren Spéculation of the Ingenious 

 Author's, but successfully practised by him ; as I can gratefully testifie, having had the favour 

 of being shewn the whole Contrivance by the Excellent Authorhimself in his Garden at the 

 Hague, Ann. 1685. at which time I had the happiness aiso of seeinghis IHanetar-j Clock, or 

 Moving Ephemeris, a Machine that cannot be sufficiently admired". On peut comparer la 

 relation (p. 528—531 du T. VIII) d'une visite rendue en 1684 à Iluygens par Thomas 

 Molyneux, frère de l'auteur de la „Dioptrica nova". En juin 1685 ce dernier visita lui-même 

 son frère Thomas qui alors étudiait la médecine à Leiden et c'est sans doute à cette occasion 

 qu'eut lieu l'entrevue entre William Molyneux et Huygensdont il est question ici. 



•7) Voir la description de cet instrument dans l'ouvrage de Huygens cité dans la note 5, p. 343 

 du T. VIII. 



