[C] _See our_ Author's Lectiones Opticae Sec. 10. _Sect. II. Sec. 29. and Sect.
III. Prop. 25._
[D] See our Author's _Lectiones Opticae_, Part. I. Sect. 1. Sec.5.
[E] _This is very fully treated of in our_ Author's Lect. Optic. _Part_
I. _Sect._ II.
[F] _See our_ Author's Lect. Optic. Part I. Sect. II. Sec. 29.
[G] _This is demonstrated in our_ Author's Lect. Optic. _Part_ I.
_Sect._ IV. _Prop._ 37.
[H] _How to do this, is shewn in our_ Author's Lect. Optic. _Part_ I.
_Sect._ IV. _Prop._ 31.