Fig. 276.—Section of the same.
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610.—Continental Form of Clinometer.—Hand clinometers on the Continent are generally made on Captain Burnier's plan, Fig. 275, which was explained for the prismatic compass, [art. 156]. Indeed this instrument is more generally combined with the prismatic compass. The graduation is set up on a plated ring vertical to the plane of the swing of a pendulum, shown in section Fig. 276. The reading index is a hair which is read on the graduation by means of a cylindrical lens, B, when this is brought coincident with the sights D′W′ as described for Burnier's compass. When the clinometer and compass are combined the vertical rims stand opposite to each other, AC. A lifter, Fig. 275, L, is provided to take the working parts out of bearing, and a stop S′ to prevent oscillation. The illustrations show the combined instrument: B cylindrical lens reading the drums; A clinometer; C compass; DD′ fore sight; WW′ windows, both of which fold down on the top of the instrument.
Fig. 277.—Major Watkins clinometer.
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611.—Major Watkins' Clinometer.[37]—The vertical plane of division is adopted, as in that of Captain Burnier, but the reading, instead of being taken on the exterior of the ring by a magnifier, which entails a projection, is placed on its interior. This reading is magnified by a concave reflector, shown Fig. 277 at R, which reads to a line on a slip of ivory placed just beside the eye-hole E shown in the engraving. The pendulum is stopped by a pin, upon which it springs when the box is rotated vertically to prevent wear when out of use. There is much less work in making this instrument than Burnier's, and the round form is more portable. The only point on which it does not bear comparison is in that the concave mirror represents a uniform distance sight which makes the reading indistinct to persons of weak sight, whereas Burnier's admits of adjustment by placing the instrument nearer to or further from the eye, the cylindrical lens being made large to admit of this form of adjustment. This instrument could be improved by the mirror being made adjustable. Weight, 6 oz.
Fig. 278.—Compass with clinometer sight.
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