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Titre : Oeuvres complètes de Christiaan Huygens. Correspondance [de Christiaan Huygens], 1666-1669 / publ. par la Société hollandaise des sciences

Auteur : Huygens, Christiaan (1629-1695). Auteur du texte

Éditeur : M. Nijhoff (La Haye)

Date d'édition : 1888-1950

Contributeur : Koninklijke Hollandsche maatschappij der wetenschappen. Éditeur scientifique

Sujet : Huygens, Christiaan (1629-1695) -- Contribution aux mathématiques

Sujet : Huygens, Christiaan (1629-1695)

Notice d'ensemble : http://catalogue.bnf.fr/ark:/12148/cb38949978f

Type : monographie imprimée

Langue : latin

Langue : français

Langue : néerlandais

Format : 23 vol. : ill. ; 29 cm

Description : Correspondance

Description : Autobiographie

Droits : Consultable en ligne

Droits : Public domain

Identifiant : ark:/12148/bpt6k778547

Source : Bibliothèque nationale de France, département Philosophie, histoire, sciences de l'homme, 4-R-788 (6)

Conservation numérique : Bibliothèque nationale de France

Date de mise en ligne : 15/10/2007

Le texte affiché peut comporter un certain nombre d'erreurs. En effet, le mode texte de ce document a été généré de façon automatique par un programme de reconnaissance optique de caractères (OCR). Le taux de reconnaissance estimé pour ce document est de 87%.

than the former, the difference being 49, fec.; the Watch hath by (b much, in days, gone too flow; which 49. Sec. divided hy the number of days, you have 7. Sec. for the daily difference; and by ib much the Watch goes too now in 24. hours. You may alfo, inftead of the Suns rifing and fetting, take two equall Altitudes of the Sun, before and after Noon, and having noted the time given by the Watches at the time of both the Obfervations, proceed with it in the fame manner, as was luft now directed for obferving the Sun in the Horizon. In either of which ways there may befome Error, caufed by the Suns Refraétion, which is inconfiderable, and therefore needs not to be taken notice of.

6.

By M~w of thefe Watches to find at Sea the Longitude of the Place, tt'A~C you are.

Give to each of the Watches a name or a mark, as A. B. C; and before you fet faile, fet them to the time obferv'd by thé Sun in the place, where you are, and whence you are departing, allowing for the Aequation of the day, whereon you make your Obfervation: Which day you are to note, if the Watches be not well adjutted otherwife it is not necefïary.

Then afterwards being at Sea, and defiring to know the Zo/M~of the place where you are, that is, how many degrees the Meridian of that place is more Eafterly or /~?/?~y, than the Meridian of that place where you did fet the Watches; you muft obferve by the Sun or Stars, what time of the day it is, as precifely as is pombie, and note at the fame time, to what hour, minutes and lec. the Watches doe point (which time, if thé Watches be not (et to the right meature, is by the known daily difference to be adju<ted,)addingthereunto the Aequation of the prefent day, which gives you the time of the day, fhew'd by the Sun, at the place where the Watches were fet: And if this time of the day be the iame with that obterv'd where you are, then you are under the famé Meridian with the place, where the Watches were (Têt by thé Sun; but if the time ofthe day, obferv'd where you are, be greater than that fhew'd by the Watches, you may be adur'd, that you are corne under a more Eafferly Meridian; and if lefs, you are corne under a more Wef ~y. And counting for every hour of différence of time, 15 degrees of Longitude, and for every minute, t~. minutes or of a degree, you fhall then know, how many degrees, minutes, ~< the faid Meridians doe differ from one another. E. g. Suppofe, the Watches A. B. C. were fet at thé place, whence you parted, on the 20 of7~ry, to the time of day obferv'd by the Sun abating the Aequation of the 20 th of~y (viz. 2 min. 28. iec.)and fuppofe that the Watch A. be <et to its right meafure, but that B. goes every day fec. too How, and C. every day t2. fec. toofait. Some days after, fuppofe the ~th of~~y, defiring to know the Longitude of the place where you are at Sea, you obferve