DE ARITITTIMETICA CALCULATORIA. 891

decuplam obſervent valoris argumentum. Præparatio igiturAbaci calculatorii ſequenti modo inſtituitur. Creta aut rubri-a ducantur in menſa aut tabula quacunque, vel atramento inArta, ſeptem line(pluresve aut paueiores, prout res exiget,0 majori aut mino calculo) ac primæ ſeu infimæ lineæ ad-0 rl atur 1, ſecundæ 10, tertiæ I 00, quartæ 1000, quintæ 10000,tu 10000& ſeptimæ oOοοο, ita ideo in una ſede novemvaleult ponantur; Ne autem confuſio exoriatur, ſi tot calculiuna ſede ſtatuerentur, conſultius eſt, quamlibet ſedem in du-partes partiri,& inter 1& 10 ponere 5, ſecundo ſpatio 50,Io goo, quarto ooo, quinto g ooοο& denique ſexto 00.2 enim fit, ut una tantum 4 calculos contineat, quod ex ap-boſito Abaco factuni vides:

Abacus calculatorius.

I ooOOοοο— 0—5 N ʒ ooo— 010 OOo— 0—ooo—1000— 00—5000—1000— o-50—100——50—1 5 N 10— 0005 5—1— 000—* J.

Quod ad uſum hujus abaci attinet, obſervanda eſt ſequensregung: quod nempe in lineis quatuor tantum calculi apponipoſſint, in intervallis unicum, ſed qui valcat quinque; ſic enimin una ſede, conſtante linca,& ſuperpoſito intervallo novemdantum ponuntur, æquivalenter, nempe unus in intervallo, ſeu1 Cuu uu ꝛ quin-