son's "Blow, bugle, blow," and called it "A Lecture to a Lady on Thomson's Reflecting Galvanometer":
And streams through narrow perforations,
The long beam trails o'er pasteboard scales
With slow-decaying oscillations—
Flow, current, flow, set the quick light-spot flying,
Flow current, answer light-spot, flashing, quivering, dying.
And thinner, clearer, sharper growing
The gliding fire! with central wire,
The fine degrees distinctly showing.
Swing, magnet, swing, advancing and receding,
Swing magnet! Answer dearest, "What's your final reading?"
Correct to tenths of a division.
To mirror heaven those eyes were given,
And not for methods of precision—
Break, contact, break, set the free light-spot flying;
Break contact, rest thee magnet, swinging, creeping, dying.
In the above verses Maxwell describes the process of taking a quantitative reading for the amount of a steady electric current; for signaling, all that is necessary is to observe the direction towards which the spot of light is going to move. It was by the reflecting galvanometer that the historic message through the first Atlantic cable was received: "Europe and America are united by telegraphic communication. Glory to God in the highest, on earth peace and goodwill towards men."
Prof. Thomson was personally engaged in the laying of the first cable. It transmitted several messages, then stopped. It served to prove the feasibility of the project which many engineers up to that time regarded as chimerical. By the labors of Thomson, Varley, Jenkin and others the construction of the cable was improved, as well as the mechanical means for laying it, and in 1866 a new cable was successfully laid, and the old one of the previous year raised from the depths and
