Approximate experimental method for the analysis of EMF waves
A 1909 technical paper from the National Bureau of Standards setting out an approximate experimental method for analyzing EMF waves, written for electrical engineers and laboratory workers measuring alternating current. The plates are line-drawn circuit diagrams with lettered components (ammeter, voltmeter, inductance, capacitance, resistance), a three-axis vector diagram of current harmonics, and set equations with radicals, giving designers spare instrument symbols, axis constructions and typeset formula blocks.
