ON MATHEMATICAL TABLES. 173 



par plnsienrs (sic) mesures entieres, a sgauoir 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 

 mais si Ton peut croire Texperience (ce que nous disons par toute reuerence 

 de la venerable antiquite & esmeu auec I'vlilite commune) certes la soixan- 

 tiesme progression n'estoit pas la plus commode, au moins entre celles qui 

 consistoient potentiellement en la nature, ains la dixiesme qui est telle : Nous 

 nommons les 360 degrez aussi Commencemens Ics denotans ainsi 360(0) * 

 & chascun degre ou 1(0) se diuisera en 10 parties egales, desquelles chascune 

 fera 1(1), puis chasque 1(1) en 10(2), & ainsi des autres, comme lesemblable 

 est faict par plusieurs fois ci deuant " f- 



At the end of the ' Appendice du Traicte des Triangles,' which concludes 

 the fourth book of the " Cosmographie " in Albert Girard's edition of 

 Stevinus's collected works, Leyden, 1634 (p. 95), there occurs the following 

 note : — 



" Notez. — J'ay descrit un chapitre contenant la maniere de la fabrique & 

 usage de la dixiesme progression aux parties des arcs avec leurs sinus, & de- 

 clare combien grande facilite en suit, comparee a la vulgaire soixantiesme 

 progression, de 1 deg, en 60(1), & 1(1) en 60(2), &c. laquelle matiere pour- 

 roit ici sembler requerir sa place : Mais veu que les principaux exemples 

 d'icelle se prennent des cours moyens des Planetes & autres comptes communs 

 avec iceux, qui jusques ici ne sont point encores descrits, nous avons applique 

 le susdit chapitre derriere le traicte d'icelles Planetes, a sgavoir en V Appen- 

 dice du cours des Planetes." 



To which is appended the following note by Girard : — " Ceste promesse ne 

 se trouve pas avoir este effectuee." 



Steichen, in his ' Memoire sur la vie et les travaux de Simon Stevin ' 

 (Brussels, 1846), p. 52, says that Stevinus promises a chapter on the manner 

 of constructing a table of trigonometrical lines " pour la division de la cir- 

 conference en parties decimales." This is not correct, as the quotation 

 from ' La Disme ' shows that Stevinus's idea was to divide the deyree cen- 

 tesimaUy. 



Briggs, in the ' Trigonometria Britannica' (p. 1), states that he was led to 

 divide the degree centesimally by the authority of Vieta (" Ego vero adductus 

 authoritate Vietae, pag. 29. Calendarij Gregoriani, & aliorum hortatu, 

 Gradus partior decupla rations in partes primarias 100, & harum quamlibet 

 in partes 10. quarum quselibet secatur eadem ratione. Atque hae partes cal- 

 culum reddunt multo facilorem {sic), & non minus certum "). We have 

 looked through ' Francisci Vietse Fontenaeensis .... Relatio Kalendarii vere 

 Gregoriani. . . .1600 " (Colophon: ' Excudebat Parisiis. . . . ,' 40 leaves, as 

 only the rectos are numbered, 1 to 40) without finding, either on p. 29 or 

 elsewhere, any mention of the division of the degree. Without venturing to 

 say that there is nothing of the kind in the book, it is not unlikely that the 

 wrong work of Vieta's is referred to, as we have found many other seven- 

 teenth-century references inaccurate ; and this is rendered more probable 

 when it is remembered that the ' Trigonometria Britannica ' was published 

 after Briggs's death. 



But granting, as is likely, that Briggs did derive the idea from Vieta, it is 

 very probable that the latter himself obtained it from Stevinus, and perhaps 

 adopted it without acknowledgment, as unfortunately it is to be feared that 



* Stevinus encloses tne exponential numbers in complete circles, for which we have 

 throughout substituted parentheses, for convenience of printing. 



t This refers to the preceding articles of the ' Disme,' where the decimal division is 

 explained. 



