The London, Edinburgh and Dublin philosophical magazine and journal of science . of the cores of the electromagnets were long straightsurfaces of iron, separated from the surface of iron placedopposite to them by only a narrow space at each pole. Inthe experiments, of which I give some results below, theintensity of the field was found, in a space about 2 , between one end of the iron core of an electromagnetand the surface of a thick piece of iron. The length of thepole-face was 30 centim. The magnet and correspondingiron were placed with their faces vertical; and a copper wirewas
The London, Edinburgh and Dublin philosophical magazine and journal of science . of the cores of the electromagnets were long straightsurfaces of iron, separated from the surface of iron placedopposite to them by only a narrow space at each pole. Inthe experiments, of which I give some results below, theintensity of the field was found, in a space about 2 , between one end of the iron core of an electromagnetand the surface of a thick piece of iron. The length of thepole-face was 30 centim. The magnet and correspondingiron were placed with their faces vertical; and a copper wirewas suspended vertically in the space between them, and in-sulated from their surfaces. The lower end of the wire dippedinto a mercury-cup, and its upper end into a second mercury-cup on the top of the electromagnet, without touching the sidesor bottoms of the cups. By means of these cups the wirecould either be put in series with the coil of the electromagnetor in circuit with an independent battery or generator. Thewire was hung in a vertical position (as shown in the diagram). from the lower end of a cord about two metres long, attachedto a firm support above, and was kept taut by two half-poundweights (represented by the single weight W in the diagram)hung at the ends of a cross bar firmly attached to the position of the wire was adjusted by shifting the point of Intensities ofPowerful Magnetic Fields. 149 attachment of the cord above until the wire was exactly oppo-site two marks, one at the upper end and one at the lowerend of the vertical central line of the pole-face. A thinthread, t1} was attached to the wire just above the electro-magnet, and carried out to one side nearly horizontally, andattached by its other end at a point near the lower end ofthe cord of the pendulum, Px. A second thread, t2, wasattached to the lower end of the wire, and carried out parallelto the thread t1} and attached to a second pendulum, P2, at asomewhat greater distance from the wire. T
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
