10.0000000 In the Triangle A B C, we have this Analogy ; As Radius 9.5742761 To the Sine of B A = 17° 43' 9.4836783 Now the Motion of 17° 43' is performed in i As 1 CP:R::tZP:cs P = 72° 17'. PROBLEM XII. The Latitude of the Place, and the Sun's Declination, given ; to find his Altitude when due East or Weft. Practice. In the two Triangles A B C, or C P Z ( fupposing the Time and Place, the same as in the last Problem ) there is given in the first Triangle ABC, the Side AC = 20° 34' the Declination, the Angle B = 50° 56' che Latitude of Chichester ; to find the Side B C, the Altitude required. VOL. II. Hh Ana Analogy. As the Sine of B = 50° 56' 9.8900929 Is to the Sine of AC = 20° 34' 9 5456745 So is Radius 10.0000000 To the Sine of the Altitude BC=26° 54' 9.6555816 In the Triangle C P Z, there is given C P, the CoDeclination, and Z P the Co-Latitude, to find the Side Z C, the Co-altitude required. For which you have this Analogy; viz. C SZP:R::csCP:cs CZ = 639 061. PROBLEM XIII. The Latitude of the Place, and Declination of the Sun given, to find the Sun's Azimuth at the Hour of Six. PraEtice. Suppose the Latitude that of Chichester 500 56', and the Sun's Declination 200 34' as it will be on the 12th of May, A. D. 1735. Then, the Diagram being prepared, you H will have therein formed, the two Rightangled Triangles ABC, and CZP, by either S of which this Problem is fatisfied. For in the Right Triangle A BC, there is the Side BC = 20° 34' the Declination, and the Angle at B = 509 56' the Latitude of Chichester, both given ; to to find the Side A B, the Azimuth of the Sun from the East or West Points of the Horizon. The Analogy is As Radius 10.0000000 To the Tangent of BC = 20° 34' 9.5742761 So is Co-sine of B = 50° 561 9.7994951 To the Tang. of the Azim. AB=13° 18' 9.3737712 Wherefore the Azimuth of the Sun at fix in the Morning is about E by N and ; and at six in the Evening, W by N and Also in the Triangle C Z P, there is given the Side CP = the Co-Declination, and ZP = the Co-Latitude ; to find the Angle at Z = the Azimuth from the North = AO. The Analogy for this is, Or varied thus, Or thus, PROBLEM XIV. The Latitude and Declination given, to find the Altitude of the Sun at the Hour of fix. Practice. In the foregoing Diagram, and in the Triangles A B C and C P Z there are given the same Things as in the last Problem, to find the Side A C in the first, and C.Z in the latter ; either of which answers the Problem. To find the Altitude AC, this is the Analogy. VOL. II. Hh 2 As As Radius 10.0000000 Is to the Sine of BC= 20° 34' 9.5456745 So is the Sine of B = 50° 56' 9.890og29 To the Sine of the Al. at six AC=15° 49'59.4357675 In the Triangle C P Z to find CZ = Co-altitude, this is the Analogy ; R:cs P Z::05 CP:csC Z= 74° 11'. Note, The Altitude in Summer, is equal to the Depresion in Winter. PROBLEM XV. Given the Latitude of the Place, the Declination, and Hour of the Day, to find the Sun's Altitude. Practice. Æ B Case 1. Let the Declination of the Sun be North 200 34' at the Hour of 10 in the Morning, or 2 in the After noon (on the 12th of May, 1735 ) and in the Latitude of Chichester 50° 56', I demand the Height of the Sun at that Time ? N According to these Data, let the Scheme be constructed as hath been heretofore taught ; then there will be formed the Oblique Spherical Triangle CZP. ; In this Triangle there is given the Side ZP = 390 04', the Co-latitude ; and the Side CP = 69° 26' the Co-declination ; and the included Angle at P= 30° oo', the Time to Noon ; to find the Side CZ the Co-altitude required. This is found by Cafe 4, in the Synopsis, thus ; As the Radius 39° 04' 10.0000000 9.9375306 9.9094022 9.8469328 Wherefore fay again ; As the Co-sine of LP=359 06! Co. Ar. 0.0871672 Is to the Co-fine of ZP=39°04' 9.8900929 So is the Co-line of LC=34° 201 9.9168593 To the Co-sine of CZ=38° 25' 9.8941194 The Complement of which to 90° = 2 B, is CB = 51° 35', which therefore is the Altitude of the Sun the Time specified. Case 2. Let the Declination of the Sun be South 20° 34'; the Latitude, and Hours as above, to find the Altitude The |