746 L. EULERl OPEUA POSTHUMA. Phys^ 



b cM ^^ b M(c — b — l) 



s ■== 



bc dM rn ^^ M{c-t-d—\) 



CD = 



(i H- 6) (1 -t- c) d-f-2 — M ' (1 -*- 6) (1 -H c) (c — l-HM)(d-i-2-.M) ' 



V bcd M j.p bcd Mjd — I) 



' (1 -f- 6) (1 H- c) (d - 1) * 4 — itf ^' (lH-6)(l-t-c)(d-l) * (d-H2-Ai)(4- J/) "• < 



«... ■ 



Pro loco oculi autem habemus EO = • Hinc cum lentium intervalla necessario sint positiva, 



oportet esse c>6-»-l et d>>2. 



19. Consideremus nunc etiam formulam, qua apparitio colorum vagorum iridis tollitur, quae 

 cum in genere sit: 



-\- etc. = 0, 



^TC — 9> ^n^ — 7i-\-(p %n^^ — n^-i-n — <p Qn'^^ — n^^ -*- n^ — n -t- f 



pro nostro casu habemus: 



11 4 i 



b-t-M c — \-i-M d-+-2 — -If 4—M 



= 0. 



Quia nunc c — 1>6 et d-*-2'^ k, ponamus c — 1 -»- Af = ,"*"' et «i -+- 2 — M = , ubi 



1 — s 1 — <? 



^ ot >? denotant fractiones unitate minores, ac nostra acquatio induet hanc formam: 

 unde litterarum 6, c, d hos eruimus valores: 



^ __ 4(2-0-(4-£-?)iW ' 



2 — 7 ' IP, 



10 — 6£ - y -I- ey — (4 — 3S - ? -4- £?)iW r*! 



(1-0(2-7) 



^__ 2-i-27-?Jtf ^ 

 1—7 



unde sequitur fore: 



^ fc £(2-S)(4-M) fe_^M_(2-0(4-M) 



■ ('— 0(1— ?)(2-7) 



i — Tj 



