The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . Fig. 12. by jerks instead of with the necessary srtioothness and the heliometer-part of Lord Lindsays heliometer was acquiredby Gill in 1879, he changed the manner of imparting the motion inquestion. A square toothed racked wheel was applied to the tubeat f (fig. 9). This wheel is acted on by a tangent screw whose bear-ings are attached to the cradle; the screw is turned by means of ahandle supported by bearings attached to the cradle, and comingwithin convenient reach of the observ
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . Fig. 12. by jerks instead of with the necessary srtioothness and the heliometer-part of Lord Lindsays heliometer was acquiredby Gill in 1879, he changed the manner of imparting the motion inquestion. A square toothed racked wheel was applied to the tubeat f (fig. 9). This wheel is acted on by a tangent screw whose bear-ings are attached to the cradle; the screw is turned by means of ahandle supported by bearings attached to the cradle, and comingwithin convenient reach of the observers hand. The tube turnssmoothly in the racked wheel, or can be damped to it at the will of. the screw attached to the heads. Accordingly, in reading the scalesA and B (attached to the slides which carry the two halves of theobject-glass), it is only necessary to turn the screws until the fixed The primary object was to have the object-glass mounted insteel cells, which more nearly correspond in expansion with became then desirable to make the head of steel for sake ofuniformity of material, and the advantages of steel in lightness andrigidity fur the tube then became evident. 228 HELIOMETER double web is pointed symmetrically on one of the divisions of scaleA, then to move the other double web by the screw S until it issymmetrically pointed on the adjoining division of scale B. Byturning the quick acting screw P (fig. 13) to the right, the cushion C(which is faced with india-rubber) presses the paperribbon (shown in fig. 13) against the index-edge andtype-wheels, and thus the beautifully cut divisions ofthe micrometer-head, the numbers marking the iJoparts of the he
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
