पञ्चसिद्धान्तिका (आचार्य वराहमिहिर - सूर्य, रोमक, पौलिश, वासिष्ठ एवं पितामह सिद्धान्त)

XIV.4 XIV. ASTRONOMICAL INSTRUMENTS 263 Fig. XIV.1 The arc NL is equal to the latitude Ø of the place, L being the point marking the latitude of the place. OL is the latitude-line drawn from 0 to meet the point L. ON is the north line. enws is the circle drawn with centre 0 and diameter d₁ d’. (The other two circles drawn with diameters d₂ d” and d₃ d’’’ are not shown in the figure). dl is the portion of the chord d₁ d’ lying bet- ween OL and ON. In the triangle Odl, Od = Rsin δ₁ dl = Od. tan Ø = Rsin δ₁.tan Ø, (1) R denoting the radius of the circle ENWS.