Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Brown, Green, Longmans, and Roberts · leaf 134
other proper mark. T to point out and read off the exact division of the circle at B, the point close to it. It is evident that, as the telescope and circle revolve through any angle, the part of the limb of the latter, which by such revolution is carried past the index F, will measure the angle… … pound microscope {fig. c\ represented in section in fig. d , and furnished with a cross in the common focus of its object and eye-glass, moveable by a fine-threaded screw, by which the intersection of the cross may be brought to exact coinci¬ dence with the image of the nearest of the divisions of…
Astronomy
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