668 ELECTRICAL MEASUREMENTS 



and the area of the curve traced while 6 goes through a complete 

 cycle will be 



area = kR \ fe cos kd d6. 



Jo 



Consequently by (11) 



area 



Similarly if the vertical displacement of P is given by 

 y = R sin (kO - |) - -RcoskO 



dy = kR sin 6 <70, 

 and the area of the curve traced by P will be 



area = Rk I /(0) sin 6 (10 



Consequently 



area 



The Chubb analyzer is a mechanism for mechanically calculat- 

 ing Ak and Bt in the manner just described. The areas of the 

 curves are determined by a planimeter as is indicated in Fig. 415. 

 The arrangement by which the point P is guided is shown in a 

 general way in Fig. 415, B and C. The first step in using the 

 analyzer is to cut out a bristol board template which represents 

 /(0), such as is shown in Fig. 415, D. The circle abc is the base line 

 from which the values of /(0) are measured, -f values of f(0) 

 being measured radially outward and values radially inward. 



The template is mounted on the turntable T, and the pin E 

 on the movable transverse rod BP is forced against the edge of 

 the template by springs. Obviously if the turntable rotates, 

 the point P experiences a displacement x = /(0). 



The frame which carries the turntable and the mounting for 

 the rod, BP, slides on the ways, RR, and by means of a crank 

 and slotted crosshead can be given a sinusoidal displacement 

 along these ways. 



Rotary motion is communicated to the turntable by means of 

 a wormwheel mounted on the axis of the turntable, and a worm 

 which slides on a splined shaft placed parallel to the ways. 



By means of a system of change gears the frame carrying the 



