th other kinds of illuminants. vanometer forced back to the left until it reaches the and twenty-four inches therefrom. The switch put- It forms a ready and convenient standard for use in the zero point; then the batteries are exactly balanced, laboratory, or even for use in gas works, and is an… … candle; at this zero reading we have also a constant upon the screen for twenty seconds; it is instantly Mr. Edison and the Society of Amateur Photogra- number of volts of electro-motive force. stopped by turning off the switch. phers are to be congratulated on their success in at A bunch of twenty…
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