schlink: hysteresis of indicating instruments 



39 



grammatically in figure i, was influenced by the following major 

 considerations : 



I. It comprises many elements typical of measuring instru- 

 ments generally, including: (a) a helical force-resisting spring; 

 (b) a Hnk work of several jointed bars; (c) a rack and pinion for 

 magnifying the motion of the parts and transmitting it to a 

 pointer rotating over a full circle of graduations; (d) a large 



Fig. I. Schematic illustration of mechanism of stabilized-platform pointer-and- 

 dial type of spring scale. It will be noted that an eccentric disposition of the load 

 on the platform is associated with a horizontal reaction in the check-rod (the lower- 

 most link shown). The friction of the terminal journal bearings of this rod is 

 proportional to this reaction, and hence to the product of the load itself and the 

 displacement of its center of gravity from the center of the platform. 



mechanical backlash (0.20 to 0.28 radian — 11° to 16° — at the 

 pointer) which is only -partially compensated by gravitational 

 force-closure. 



2. The independent variable, viz, the load weighed, is essen- 

 tially nonhysteretic and, therefore, admittedly reproducible 

 with very high precision. 



3. The aggregate fractional resistances of the apparatus 

 are inherently large and moreover subject to ready control 



