OF ARTS AND SCIENCES: JANUARY 9, 1866. 67 



over the same figure on the dial-plate ; but when a strain is put 

 upon the belt and the round rod moves laterally, as above described, 

 the lateral motion brings a conical enlargement of the rod under the 

 little belt which moves the wheel bearing the dial. The dial-wheel 

 now goes faster than the wheel carrying the hand, and begins to 

 count up the power used. The greater the lateral motion of the 

 rod, or, in other words, the greater the power transmitted to the 

 working machines, the larger the diameter of the cone which comes 

 under the belt of the dial-wheel, and the greater the gain of the dial 

 upon the hand. The wheels of both dial and hand are constantly re- 

 volving in the direction opposite to that of the motion of the hands 

 of a watch. The 'belt of the hand-wheel runs always upon the rod, 

 where its diameter is constant, and as the rod moves laterally under 

 the little belts, guides are necessary to keep the belts themselves from 

 moving laterally also. The proportions of the cones on the rod, and of 

 the two wheels which carry the dial and the hand, can be so adjusted 

 as to make a difference of one complete revolution between the motions 

 of the hands and of the dial indicate a delivery of ten thousand foot- 

 pounds, or of ten million, or of any other convenient number, and, by 

 a system of gearing analogous to that used in gas-metres, any desired 

 amount of power could be consecutively registered. It is obvious 

 that the registering apparatus takes account of both the strain and 

 the speed, while the simple index first described measures only the 

 strain. 



This instrument is at once elegant in design, simple and therefore 

 cheap in its construction, easily verified and proved at any moment 

 when in operation, and of very easy application to any machine, or set 

 of machines, driven by hired power, whether the power used be con- 

 stant or variable in amount. The instrument admits of a great variety 

 of forms : the one described above is meant for the end of a shaft ; 

 another form is so arranged as to be attached at any part of a running 

 shaft, while in the proportions and dimensions of the several parts there 

 would be the same variety as in common scales, which are large or 

 small, coarse or fine, according as they are meant to weigh coal or pills, 

 hay or coin. The instrument meets a pressing want. Tea and sugar 

 are sold by the pound, gas by the thousand feet, cloth by the yard, but 

 steam-power and steam and air engines are sold by guesswork, or by 

 rough and uncertain rules, on whose application buyer and sel!er can 

 seldom agree. 



