. Physical laboratory experiments : mechanics, optics and heat. s, the area of each ofwhich may be computed from linear measurements. Object.—^The object of this experhnent is to afford practicein the manipulation of the Amsler planimeter, to test theaccuracy of the instrument, and to become familiar with therelative values of the units of area in the English and Metric 12 PHYSICAL LABORATORY EXPERIMENTS systems. The experiment also gives practice in the use ofthe dividing engine. Apparatus.—The type of Amsler planimeter provided isshown in Fig. 3. It consists of two arms hinged together,one o
. Physical laboratory experiments : mechanics, optics and heat. s, the area of each ofwhich may be computed from linear measurements. Object.—^The object of this experhnent is to afford practicein the manipulation of the Amsler planimeter, to test theaccuracy of the instrument, and to become familiar with therelative values of the units of area in the English and Metric 12 PHYSICAL LABORATORY EXPERIMENTS systems. The experiment also gives practice in the use ofthe dividing engine. Apparatus.—The type of Amsler planimeter provided isshown in Fig. 3. It consists of two arms hinged together,one of which is pivoted at the end by the needle point F, whilethe other, the tracer-arm, carries a point P, which iscaused to trace the outline of the area to be measured. Theplanimeter rests at Z) on a roller-wheel so mounted on thetracer-arm that it slides without rotation when moved in thedirection of the arm A, and rotates without sliding whenmoved at right angles to this direction. Motion in all otherdirections is accompanied by sliding and rotation. The. Fig. 3. number of complete revolutions made by the wheel D isrecorded on the dial G, while fractions of a revolution maybe noted by means of the vernier E, which reads to ofa revolution of D. The effective length of the arm A can bevaried by clamping the sleeve carrying the hinge and record-ing mechanism at any desired position by the screw S. Theexact adjustment at any desired division on A is made bythe fine adjustment screw below S. The tracer-arm A isgraduated at three points such that when the planimeter isset exactly at these positions, the instrument records areas insquare decimeters, ten square inches or tenths of a squarefoot respectively. The instrument may thus be used tomeasure areas directly in any one of these units.^ The planimeter is a delicate and expensive piece of appa-ratus and should be handled carefully. It should be wiped IFor an elementary explanation of the theory of the instrument see Peabo
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Keywords: ., bookcentury1900, bookde, booksubjectmechanics, booksubjectphysics
