Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
reflected,converging, to the eye-piece, L. The size of the tube and the inclina-tion of the axis of the speculum are so adjusted, that the observer doesnot intercept any light which can fall upon the reflector. This is called the front-view telescope. The speculum of Herschelsgreat telescope was 4… … 4-92. Figure 25.—The Gregorian reflecting telescope.— M is a concave metallic speculum, having a hole in its centre. This 27G OPTICS. Fig. 36. reflector will form, at its focal distance, an inverted image, L. At T isplaced a small concave mirror, about oue-lburth the focus and diameterof the…
Physics · Astronomy
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