action notwithstanding

  
<p>action notwithstanding</p>
<p>The next pendulum of'EUicot's any importance it is necessary to speak of is that of Mr. pendulum, Ellicnt, the description of which we give nearly in his own words. It is represented in fig. 5, in which a b Fig. 5.is a bar of brass, made quite fast at the upper end by pins, and held contiguous to the rod of the pendulum which is of iron, at several equal distances, by the screws ? ?. The pendulum <a href="http://www.coachsoutlet-storeonline.com/"><strong>Coach Factory Outlet Online</strong></a> rod as far as the brass extends is made of the same figure; but a little below the end of the brass bar, the iron is left broader for the convenience of fixing the work to it, and is made of sufficient length to pass through the ball of the pendulum C. The holes in the brass through whicli the screws pass into the iron rod are made of sufficient length to permit the brass to contract and dilate freely by heat and cold under the heads of the screws: ff represent two strong pieces of steel or levers, whose inner centres or pivots turn in two holes drilled in the broad part of the pendulum rod, and their outer ones in a strong ridge screwed upon the same part of the rod, but omitted in the drawing, in order to exhibit the internal mechunism; g g are two screws entering at the edge, and working in the cavity near the centre of the ball. The ends of the screws next the rod are made of the figure shown in the drawing, which pressing with the weight of the ball against the lower arms of the levers cause the short ends to press against the brass bars at 6. The parts being adjusted in this situation, let us suppose the rod of the pendulum and brass rod annexed to it to be elongated by heat. As the brass lengthens in a greater degree by <a href="http://www.coachsoutlet-storeonline.com/"><strong>Coach Outlet Store Online</strong></a> the heat, it will force the short ends of the levers downwards, and at the same time necessarily lift up the ball, which rests on the long ends of the same levers at ff, to any proportion necessary, and, provided the ends of the screws press upon the levers at a proper distance from the centres or pivots, the ball will be always kept at the same distance from the point of suspension, notwithstanding any alteration the rod <a href="http://www.coachsoutlet-storeonline.com/"><strong>Coach Outlet Online</strong></a> of the pendulum may be liable to from heat or cold. What this distance ought to be may be determined, if the difference of expansion between the brass and iron is known, for the proportion the shorter arms of the levers ought to bear to the longer ones will always be as the excess of expansion <a href="http://www.coachsoutlet-storeonline.com/"><strong>Coach Outlet</strong></a> of the brass to the whole expansion of the iron.The correctness of the principle of this instrument, although so obvious as scarcely to require demonstration, is founded upon the supposition that the pendulum rod is perfectly inflexible, and that all the parts move without friction, in which case the operation must be perfectly smooth and uniform; but as Mr. Cummings remarks, in his excellent Treatise on Clockwork, if the pendulum rod be in any degree flexible, or friction take place in any part, which of course must always be the case in practice, the operation must be attended with a degree of irregularity of motion, which, although imperceptible to the sight, must affect the accuracy of the instrument. To remedy these evils, Mr. Cummings proposed that three bars should be made use of, one of brass and two of steel, firmly connected at one end, and held together by any determinate power towards the other; here the steel bar being situated on each side of the brass, endeavour by means of the limited power which connects them to bend it, each operating in its own way, so that they counteract and destroy each other's defects.This construction will be understood by inspecting fig. 6, 7, 8 of the plate, where fig. 6 is a front view of the bars connected together, fig. 7 a side elevation of the same, and fig. 8 a front elevation of the brass bars separate. The bars s s, as they move on the surface ofthe intermediate bar, by the different contraction and Mechauicul expansion of the metals, press upon the piece of metal Piowbm-s. C in such a manner that each should have equal action notwithstanding the inaccuracies of execution, and a greater degree of regularity produced than could be attained by the two rods alone. Ellicot's pendulum, constructed in this manner, Cummings conceived to equal in many respects the gridiron pendulum, with the advantage of being more easily and accurately adjusted.(892.) </p><br/>