...fucb a manner, that they may all converge to the fame Point in its Axis, or unite in one Focus nearly, The Ratio of the Sines of the Angles of Incidence and Refraction of the fever al Sorts of Rays being refpeftively given, and allowed conflant and immutable, according...

...but a point. Let x=the sine of the angle of incidence, and therefore VI — xx=its cosine, r=l; put the ratio of the sines of the angles of incidence and refraction, as 1 : p, then 1 : p : : x : px=the sine of the angle of refraction; and Vl — pjx"= its cosine. The...

...and the sun's altitude, observed at the same time, he found the angle of refraction, and consequently the ratio of the sines of the angles of incidence and refraction, for the mean refrangible rays. The celebrated Euler suggested a method of measuring the refractive...

...fathom-intervals are exaggerated nearly in the ratio of 6 to 8 or 3 to 4 : — that is, sensibly in the ratio of the sines of the angles of incidence and refraction for water. This is only true for small angles of incidence, that is, for the lower fathoms ; for, in...

...one medium to another, the change which takes place in if" direction is expressed by saying, that ' the ratio of the sines of the angles of incidence and refraction is invariable for the same medium.' This we shall endeavour to explain. Let a vessel which is a hemisphere...

...difference of less than half a degree each way. When we consider how simple the law of refraction is, (that the ratio of the sines of the angles of incidence and refraction is constant for the same medium,) it appears strange that a person attempting 5 Optica, p. 411. " LUK...

...difference of less than half a degree each way. ' When we consider how simple the law of refraction is (that the ratio of the sines of the angles of incidence and refraction is constant for the same medium), it appears strange that a person attempting to discover it, and drawing...

...assumes the form * The truth of the first of these equations (sin £ = m . sin 7) which merely expresses the ratio of the sines of the angles of incidence and refraction is obvious ; but owing to the great number of small angles about C, a little consideration may be required...

...each transparent medium has its own particular refracting power, but for the same transparent medium the ratio of the sines of the angles of incidence and refraction is always the same. 980. Index of refraction. — The number which thus expresses the ratio of the...

...again, and thus take ten or fifteen readings between B and D. Now from these readings to prove that the ratio of the sines of the angles of incidence and refraction is always constant and equal to the index of refraction. In the figure, the angle of incidence equals...