Emerson, William, 1701-1782 · London : Printed for J. Nourse · leaf 255
Lai. 35I, N. July 31, 1767, ai 10 oclock. Gnomonically. ■ 5_ To projccl the upper hemifphere on a plane pa-rallel to the horizon. With the radius of projec-tion and center C, defcribe the primitive circleADB. Thro C draw the meridian PE, and ASperpendicular to it for the prime vertical. Setoff CP… … r Sea. III. OF THE SPHRRE. 57 equino6lial. Make EB 30° (or 2 hours) and draw Fig.the 10 oclock meridian PB. Set the funs dechna- ^t>.tion 18° 27 from B to 0. And O is the place ofthe fun at 10 oclock. Thro O draw the azimuthcircle CQ^i likewife thro 0, a parallel to the equi-nodtial EQ^may…
Mechanical engineering
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