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Titre : The chronology of ancient nations : an English version of the Arabic text of the Athâr-ul-Bâkiya of Albîrûni or "Vestiges of the past"... / transl. et ed. with notes and index, by Dr. C. Edward Sachau,...

Auteur : Bīrūnī, Muḥammad ibn Aḥmad Abū al-Rayḥān al- (0973-1050). Auteur du texte

Éditeur : W. H. Allen (London)

Date d'édition : 1879

Contributeur : Sachau, Eduard (1845-1930). Traducteur

Notice du catalogue : http://catalogue.bnf.fr/ark:/12148/cb301077601

Type : monographie imprimée

Langue : anglais

Format : XVI-464 p. ; in-8

Format : Nombre total de vues : 483

Description : Contient une table des matières

Droits : Consultable en ligne

Droits : Public domain

Identifiant : ark:/12148/bpt6k728990

Source : Bibliothèque nationale de France, département Philosophie, histoire, sciences de l'homme, 4-G-107

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 81%.

(no parabole and hyl,erbolas). AU this is cïp~ined in my book which gives a complete représentation of all possible méthode of the construc tton of thé astrolabe.

However, lines, cireles, and points do not represent themselves in the same way on a plane as on a globe for the distances which are equal on a globe differ greatly in a plane, espeeially if some of them are near to the one pôle and others to the other pole. But it ia not the purpose of the astrolabe to represent them (the lines, cireles, points) M agreeing with eye-sight, but to let some of them revolve whilat the p.358. others are rest, so that the reault of thM process agrees with the 10 p, appeat-McM in heaven, including the dieerenoe of time. On the other hand, the purpose of the representation of the starn and countriea (onevenphnes)M this, t. make them correspond with their position in heaven and earth, so that in looking at them you may form an idea of their situation, always keeping in mind that the straight lines are not lite the revolving (circular) lines, and that thé apherM planes have no liteness to the even planes that are equal among eaeh

other.

Wemust give an illustration to make the reader familiar with thèse methods. One way serving for this purpose is the construction of the 20 flat astrolabe.

Draw a circle aa you like it, the greater the better. Divide it into four parts by two diameters which eut each other at right angles Divide one of the radii into 90 equal part<. Then we make thé centre of the circle a new centre, and describe round it circles with the distances of each of the 90 parts. These circles will he patanei to each other, and will be at equal distances from each other. Divide the ch-cumference of the greatest circle into the (360) parts of a circle, and connect each part of them and the centre by straight lines.

In doing this we imagine the periphery of this first circle to be the to ecliptic, and its centre to he one of the poles of the ecliptic. On the eehpuc we mark a point as the beginning of Aries. Then we nx the places of the stars according to AImagest, or to thé Canon of Muhammad b. J~ir AlbattSni, or to the of FM by 'Abû-AJhusain AIsuS, taking into account thé a of precession up to our time, and changing accordingly the places of the stars as determined by our predecessors. Take one of the stars of that half (of heaven) for which you have constructed this circle, and count from this assumed point (the beginning of Aries), proceeding from right to left, as many degrees as the star is distant from Aries. That place where you arrive is the 40 degree of this star in h~t<M<~e.

Further count, from the same point in a straight line which extends to the centre, the corresponding number of the star's latitude in the 90 cudes. Then the place you arrive at is the place of the body of the stars (i.e. the point determined by both the degrees of longitude and