AN ELECTRIC POWER METER.

Waikato Times, Volume XVIII, Issue 1500, 14 February 1882, Page 2

AN ELECTRIC PO WER METER.

At a recent meeting of the Physical Society, Mr 0. Vernon Boys exhibited and described a very ingenious new integrating machine of his invention, and its application as a measurer ot electric energy in the circuit of au electric lamp or a dynamo-electric jmotor. Mr Boys' mechanical integrator belongs to the class termed tangent machines, and consists esseutially of a small disc or -wheel running along the surface of a drum or cylinder. When the wheel runs straight along the drum parallel to its axis there is no rotation of the latter, but when the wheel is inclined to the axis the drum rotates, and the intregal is represented by the amount of rotation, Continuous action is secured in giving the drum a reciprocating or to»and<fro motion along its axis, so that when the wheel has travelled to one end of the cylinder it can travel back again. The new integrator is especially adapted for measuring forces which are either delicate or variable, because, unlike other integrators, the inertia and friction of the moving mass or wheel is so slight as to be quite inappreciable. It is applied by causing the varying force to be measured to vary in a corresponding manner the inclination of the wheel to the axis of the rotating cylinder. In this way it can be used to find the work done by a fluid pressure reciprocating engine, or the energy transmitted by a shaft or belt from one part of a factory to another. Moreover, by making the wheel very small and light, the strength of an electric current may be continuously measured, if the disc is inclined by means of the needle of a galvanometer in circuit. Mr Boys has constructed, on the same principle, an electrio energy meter which integrates the product of the strength of current and the difference of potential between two points with respect to time. In it the current is passed through a pair of concentric solenoids or coils of wire, and in the aunlar space between these is hung a third solenoid, , the upper half of which is wound in the opposite directionto its lower half. By the use of what Mr Boys calls " induction traps" of softipoi), the migiietie fQrce 'is, confined, to a small- pprjaqn of = suspended sqleiioid qajd by this means the »ajitra.cting,forcp .of the fixed solenoids upon it >is indepen: dent of position. .The middle solenoid is) hung from the Vn<i v of ' J aT balance, beam, and its' motion is retarded By V counterweight, wiiclj admits 6i regulating the meter to give" : staridatiFto 1 measure as a lclock,gi\;es standard. v tinj§ A ,, TJjg.jnotion of "" the "beam is caused to -incline the' integrating I wheel, -"arid* the roto- 1 tion of the cylinder gives the" ene'rgy'expen'ded in" foqt-sou'n"4sf t b ) y>' means 'indicator; or diagram,' as ,the cage mpy ,be, object intgiving^ah^ equal .nuinberQf tuVnsln 6pp^Bil»4t4ii*6*otions^^,th^^ B)j§pended spLtooidf^H»^en% merit ,' iiisensibU^p>^eHi^ma| 'jj|agnetic. at i Ws6tjrisfJ%asiq&<le for tyf]