Herschel, John F. W. (John Frederick William), Sir, 1792-1871 · London : Longman, Rees Orme · leaf 102
ost conve-nient means of ascertaining the horizontal point, is thatafforded by the floating collimator, a recent invention ofcaptain Kater. This elegant instrument is nothingmore than a small telescope furnished with a cross-wirein its focus, and fastened horizontally, or as nearly soas may be, on… … limator be illuminated by a lamp, being in the focus ofits object-glass, the rays from them will issue parallel,and will therefore be in a fit state to be brought to afocus by the object-glass of any other telescope, in 96 A TREATISE ON ASTRONOMY. CHAP. II. which they will form an image as if they…
Astronomy
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