The description and use of the universall quadrat.: By which is performed, with great expedition, the whole doctrine of triangles, both plain and sphericall, two severall wayes with ease and exactness. Also the resolution of such propositions as are most usefull in astronomie, navigation, and dialling. By which is also performed the proportioning of lines and superficies: the measuring of all manner of land, board, glasse; timber, stone. &c.
Stirrup, Thomas.
CHAP. XX. Having the distance of the Sun from the next Equinoctial point, to finde his right ascension.
- AS the radius,
- To the cosine of the greatest declination:
- So is the Tangent of the distance,
- To the Tangent of the right ascension.
Thus in the right angled Triangle ♈X♉ in the Dia∣gram of the 6 Chap. having the angle X♈♉ the Suns greatest declination 23 deg. 30 min. and the base ♈♉ the distance of the Sun from the equinoctial point ♈ 30 deg. with the right angle at X, we may finde the side ♈X the Suns right ascension by the 33 Chap. of the second Book.
For if we place the threed at the intersection of the contrary sine of 90 deg. with the right tangent of 30 deg. it will cut the contrary sine of 66 degrees 30 minutes, at the right tangent of 27 degrees 54 minutes, and so much is the side ♈X the right ascension required,
