Between the two poles a strong current is excited, & on moving the magnet around we magnetize the bars to saturation i.e. The touch in a circuit is by forming a circuit with the bars, and moving the horseshoe magnet backwards and forwards upon it. &c The double touch is by taking two magnets, joining them by their opposite poles, making an obtuse angle, bringing these ends on to the middle of the bar, and drawing each to the end &c. We magnetize, first by the simple touch (?)e by rubbing a piece of iron from the middle to one end, with the north end, of the magnet, and from the middle to the other end, with the south end. It is necessary to have some force to begin with, and it may be derived from the earth as above mentioned – or by twisting wire -or by hammering punching &c. The power resides in the iron and is only developed by the presence of the magnet, as shown by the magnet’s losing none of its power. A piece of soft iron held perpendicularly & struck slight-ly becomes magnetic and may be used for magnetizing the steel. “Steel is rendered magnetic in different ways & once magnetized retains its power for a long time. “The directive force of a magnet is its tendency to point to the north pole of the earth, and the translative, its tendancy to move to the north pole or to another magnet, &c. Joseph Henry Lectures on Natural Philosophy (Henry C. These magnets can then be used to induce magnetism by the methods given above.Īdditional Excerpts Relating to Henry’s Methods of Making Permanent Magnets Hang a bar vertically for a lengthy but unspecified amount of time (probably a few days to a week or so).Strike a bar, either held vertically or pointed north, (some sources say soft iron and others say hardened iron or steel) several times on one end with a hammer.
Two bar magnets can be substituted for the horseshoe magnet, and a group of six magnets can be more strongly magnetized by using two as a horseshoe and then substituting them with two from the circuit and so on.
While one source says it should be moved “backwards and forwards”, the rest agree that the magnet should only be moved in one direction (which makes sense), then slid off onto a piece of soft iron. Touch in a circuit – form a circuit (square) with four bars and move a horseshoe magnet over it.Double touch – take two magnets, touch the south pole of one and the north pole of the other to the center of the bar, and draw them off to the ends a number of times.Simple touch – rub the north pole of a magnet from the middle of the bar to one end, and the south pole from the middle to the opposite end an equal number of times.Summary of Henry’s Methods of Making Permanent Magnets Put them in a bundle with their North poles the same way and we will have a magnet for making others with.”
Take a small bar of steel magnetize it by percussion, and then magnetize several small bars. This process is affected by induction accelerated by friction. Take the horse shoe magnet, place it in the middle of the needle to be magnetized and draw it over one half of the needle an equal number of times. Take a steel bar, hold it vertically, and strike the end several times with a hammer, and it will become a permanent magnet. Draw them towards its ends, repeating the process several times. Take two magnets put one North pole and one South pole on the middle of the iron. Lay a piece of iron on the table and put the north pole in the middle and draw it over half the iron, than put the south pole on and draw it over the other half.
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