Page 508 | Volume 2 | Chapter 27 | Testing and Testing Apparatus
Change the rheostat resistance accordingly until the balance attained is such that a very slight variation of the rheostat resistance one way or the other will reverse the galvanometer deflection. To find the pressure on the circuit, add 100 to rheostat resistance and point off two places. Multiply this value by the voltage and the product will be the desired voltage.
If the voltage of the standard cell be exactly one volt, the total employed resistance represents the voltage on the circuit.
When first published in 1914, these books were intended to explain the scientific principles of electricity (which at the time was a new and exciting technology) with "the aid of a very large number of illustrations, together with specific explanations, worded in concise and simple language".
What really makes this collection of books special today is the detailed documentation of most of the earliest inventions in electrical history including telegraphs, motors, switchboards, and high power distribution systems.
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