We can, therefore, with this arrangement, receive on the galvanometer, just as on the mirror galvanometer used in submarine cable work, a dot or dash, and, moreover, the magnitude of these deflections is a measure of the energy of the wave.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming
He described fully how the direction and magnitude of the needle deflections varied with the relative position of the wire, and the polarity of the battery, and stated "From the preceding facts, we may likewise collect that this conflict performs circles...."
"The Earliest Electromagnetic Instruments"
Robert A. Chipman
By a separate experiment, he showed that the vertical sides of the loop would also increase the deflections.
"The Earliest Electromagnetic Instruments"
Robert A. Chipman