... of another operating installation and use the same settings of that installation, or determine the required voltage experimentally. ... If continuous control is required on the d.c. line, a potentiometer-type circuit is used (slide-wire resistance shunted across the cell). ... Current will be between 0.2 and 3 amp. ... Etchant: 10% oxalic acid 7 a Structure Similar to Fig. 6, Finer Grain. 500 X- Flat sur- starting from 00 emery paper Fig. 1 a Spider for Hamilton Variable Pitch Propeller Supported.