212 Description of the Newcastle Dynamometer. 



page 206, that such is not the case, but that the increments of 

 strain on the rope become continually larger for equal increments 

 of deflexion of the spring as it approaches y. It is obvious, then^ 

 that some device must be adopted to compensate for this irregu- 

 laritv, and to make the disc-wheel F move over the disc-plate 

 G, Fig. 3, through spaces proportional to the increasing strains- 

 on the rope. The diagram, Fig. 4, will show how this adapta- 

 tion of the " Totalisateur "' has been oflfected. 



In Fig. 4, G represents the disc-plate, A A represent 

 parts of the framing for carrying the instrument, to which are 

 fixed two bearing-blocks, b h, through which the bar c slides, 

 freely, on this bar are keyed two arms d d, and through the ends, 

 of each of these a screw is passed, the pivot-points of which carry 

 the spindle upon which the disc-wheel F and the index of the 

 counter E are fastened ; while a spring s, upon the bar, retains 

 the whole in position with the disc-wheel F at the centre of the 

 disc-plate G, when all is in a state of rest. 



M is the central pulley of the dynamometer, which for per- 

 spicuity is shown with the resisting spring (S, Fig. "1) removed. 

 J is a plain block-wheel revolving on a fixed j)in, and to tlu? 

 edge of that wheel a thin riband of steel, L, is fastened, partly 

 round it and from it to the crossbar N, which is connected by 

 rods with the centre of the pulley M. K is a cam, fastened to 

 the block-wheel, and revolving with it upon its centre. 



It will be seen that the end of the bar c, now in a state of rest, 

 presses upon the inferior diameter of the cam K. and when the 

 strain is put on the wire-rope, the pulley M is deflected in the 

 direction of the arrow on its left, the block- wheel J, and the cam 

 K, are turned round by the action of the riband L, and the 

 superior diameter of the cam K, continually increasing, com- 

 presses the spring *•, and forces the bar c, with its adjuncts, 

 towards X, and the disc-wheel F, is carried onwards from i 

 towards^', on the surface of the disc-plate G. 



The cam K is constructed in such a manner that its ordinates 

 increase in a manner corresponding to the decreasing deflexions 

 of the spring S (Fig. 2) when approaching f, so that the disc- 

 wheel F is moved by the action of the cam over the surface of the 

 disc-plate G, with velocities which are in exact accordance with 

 the increasing or decreasing strain on the wire-rope. Hence the 

 results may be read on the counter, E, in the manner before 

 described. 



