[Coffin, John Huntington Crane], 1815-1890. [from old catalog] · New York, D. Van Nostrand · leaf 70
lem 17. To find the distance of an object ofknown height, which is just visible in the horizon. Solution. If the observer isat the surface of the earth atthe point H/; (Fig. 15), a pointA appears in the horizon, or isjust visible, when the visual rayA W just touches the earth atH. Let h = B A, the… … Fig. 15. sin iHCA = f /\h(R+\K) 42 R2 or nearly and i H C A sin 1 W; 84 £? HCA sin 1= i/III. y 21 r 64 NAVIGATION. This, substituted in the expression for c?, gives *-**VS«y (■£•**); (») In this, <#, A, and J? are expressed in the same denomina-tion. But if h and B are in feet, in statute miles,…
Navigation · Nautical astronomy
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