[C] _See our_ Author's Lectiones Opticæ § 10. _Sect. II. § 29. and Sect. III. Prop. 25._
[D] See our Author's _Lectiones Opticæ_, Part. I. Sect. 1. §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. § 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.