Page 4-5 Isaac Newton Book

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D E F I N. V.

The Angle of Refraction, is that the Angle that the road defcribed by the reftected or refracted Ray containetb with the Perpendicular to the reflective or refracting Surface at the purpose of Incidence.

D E F I N. VI.

The Sines of Incidence, Reflexion, and Refraction ar the Sines of the Angles of Incidence, Reflexion, and Refraction.

D E F I N. VII.

the sunshine whofe Rays ar all alike Refran- gible, I decision straightforward, Momogeneal And Similar; which whofe Rays ar fome additional Refrangible Than others, I decision compound, Heterogeneal and Diffimilar.

the previous light-weight I decision Homoge- Neal, not becaufe i'd affirm it of altogether re- fpects; however becaufe the Rays that agree in Re- frangibility, agree at leaft altogether thofe their different Properties that I confider within the following Difcourfe.

D E F I N. VIII.

the colors of Homogeneal Lights, I decision Pri-mary, Homogeneal and Simple; and thefoe of Heterogencal Lights, Heterogencal and Com- pound.

For thefe ar perpetually Compouned of the colors of Homogeneal Lights; as can ap- pear within the following Difcourfe.

A X I O M S.

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A X. I.

T B E Angles of Reflexion, and Refraction, lie one and additionally the celebrity Plane with the Angle of Incidence.

A X. II.

The Angle of Reflexion is up to the Angle of Incidence.

A X. III.

If the Refracted Ray be came back directly back to the aim of Incidence, it fball be re-fracted into the road before defcribed by the in-cident Ray.

A X. IV.

Refraction out of the rarer Medium into the denfer, is made towards the Perpendicular, that is, of that the Angle of Refraction be lefs than the Angle of Incidence.

A X. V.

The mathematical function of Incidence is eitber accurately or really nearly terribly} very given relation to the mathematical function of Re-fraction.

wherefrom if that Proportion be acknowledged in anybody Inclination of the incident Ray, 'tis acknowledged in all the Inclinations, and thereby the Refra-ction in all cafes of Incidence on the celebrity refra-cting Body may even be determined.

therefore if the Refra-