Fig. 12.—Curve obtained by Measuring Apparatus.
(The dotted lines show the pressure on taking off the load.)
An apparatus free from this fault is shown in Fig. 13. It consists essentially of a counterbalanced lever A, to which the upper jaw J is rigidly attached. By means of a sliding weight W, any desired load, from zero upwards, may be put on this jaw. The lever carries a very delicate spirit level, which allows it to be set accurately horizontal in every experiment. The lower jaw is movable vertically between parallel guides, and its position is controlled by the screw-wheel S which bears a divided circle on its circumference. The position of this wheel, and therefore of the lower jaw, may be accurately read on the vernier v. In every experiment it is adjusted so as to make the upper lever accurately horizontal.
Fig. 13.—Improved Apparatus for Measuring the Degree of Falling. (Sand.)