Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Rees Orme · leaf 91
onof the telescope is truly at right angles to the axis, anddescribes strictly a plane, i. e. marks out in the heavensa great circle. In good transit observations, an error oftwo or three tenths of a second of time in the moment * See Dr. Pearsons Treatise on Practical Astronomy. Also BiancbiSopra… … to point out and read off the exact division of the circleat B, the point close to it. It is evident that, as thetelescope and circle revolve through any angle, the partof the limb of the latter, which by such revolution iscarried past the index F, will measure the angle de-scribed. This is the…
Astronomy
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