Magic, Pretended Miracles, and Remarkable Natural Phenomena

by Anonymous

Mrs. Somerville, well known for her excellent philosophical works, made some experiments on the effect of solar light in the production of permanent magnetism. If half of a small sewing needle be covered with paper, and the exposed part be placed in the violet or indigo ray, magnetism will be induced, and the same effect will be produced in a smaller degree by the blue and green.

To describe but one more mode; magnets are readily made by what is called the single touch, and this is perhaps the most simple and most effective way of proceeding. Place the steel bar to be magnetized on a table, or any other convenient place, and, as nearly as possible, north and south, which position is called by philosophers, the magnetic meridian. This being done, draw over it perpendicularly a strong magnet. In this operation, it is necessary to begin at one end of the bar, and draw the magnet over its entire length, and then again in the same direction. It must not be drawn backward and forward, for the power communicated in one direction, would be destroyed by an opposite motion.

The following experiments are very instructive:—Suspend a magnetic needle by a silk cord, so that it will hang in a horizontal position. Then bring it over the centre of a large magnet lying upon a table, and it will still retain its position; but, as it is brought near to either end, it will be bent downwards, and, at the extremities, will be vertical. This experiment illustrates what is called the dip of the magnet. On the equator of the earth, the needle is horizontal, or nearly so, but as it is brought near the poles it dips, and over either magnetic pole would be vertical. The reason of this is evident from the former experiment: at the equator, each pole of the needle is attracted in an equal degree by the north and south poles of the earth; but, if we proceed northward, the north pole of the magnet will be more attracted than the south, and point towards it until at last it becomes vertical. The poles of the earth’s rotation, that is, the points which would form the terminations of its axis, did it revolve on one, are not the magnetic poles; nor is the equator of the earth the magnetic equator. They do not, however, greatly vary.

Take, also, a bar magnet, and, placing it upon a table, cover it with a sheet of writing-paper. Then sprinkle upon it some fine iron filings, and they will arrange themselves in very beautiful curves round the magnet, showing, as it is supposed, the circulation of the magnetic fluid. From this experiment, we learn that the magnetic power is greatest at the poles; and this is true in reference to the magnetism of the earth, which increases in power from the magnetic equator to the magnetic poles of the earth, as determined by a great variety of interesting and delicate experiments. Sir Graves C. Haughton has communicated a paper to the June number of Brewster’s Philosophical Magazine, entitled “Experiments proving the common nature of Magnetism, Cohesion, Adhesion, and Viscosity.”

This paper contains two separate sets of experiments, the first of which relates to the attraction the magnetic needle has for various mineral, vegetable, and animal substances: and it is not a little remarkable that antimony and bismuth, as well as copper, tin, and cadmium, are, in these experiments, shown to have attractive powers for the magnetic needle; though, in those made by Dr. Faraday, he has ranged them amongst the class of dia-magnetics, that is, of those that exhibited repulsion. Arsenic, too, which he found so intractable, was made, in the present experiments, to assume the real magnetic character, that is to say, the power of attracting and repelling, by being kept for a short time in contact with a bar magnet. Iodine, likewise, was found, on bringing it near the needle, to be able to attract it.

In most of these experiments, the needle was made to attach itself to the substances by being forced towards them by a magnet, which was gently withdrawn after contact was so effected. In this way, and by a reference to the degrees of the compass traversed by the needle, a hair of the head, or a spark of diamond, can be accurately measured. The strength of the needle in its movement on a pivot was ascertained by azimuths, of which a detailed account is given.

The remainder of the memoir, which is contained in a supplementary number of the Magazine, is devoted to a detail of about five hundred experiments, in which non-ferruginous needles were made, by a modification of the magnetic needle, of which they formed a portion, to attach themselves to the same substances as in the preceding experiments. Thus, for instance, needles of most of the remarkable metals, as well as of glass, were found to have a strong affinity for nearly every kind of substance, whether mineral, vegetable, or animal, if its density was greater than that of cork or charcoal. Brass surpassed all the metals in its power of attraction, and, what is most remarkable, the magnetic needle was the lowest of all in the scale, showing not much more than one-third of the attractive energy of soft iron. Every substance of a crystalline or vitreous character exhibited remarkable magnetic properties, and this could not be mistaken, as it might be heightened at pleasure by contact with either pole of a powerful magnet. Towards the close of the experiments, the curious discovery was made, that needles of ivory, mother-of-pearl, tortoise-shell, horn, etc., were singularly magnetic, and this is traced to the albumen and gelatine they contained; and the inference is drawn, from this and other facts, that the cohesive, adhesive, and viscous properties of bodies are owing to real magnetic qualities, and that, by drying, albuminous, gelatinous, and glutinous fluids constitute various kinds of glass, which view is supported by what takes place with the gelatinous hydrate of silicium.

“The preceding experiments,” says the writer, “include a vast variety of substances in the mineral, vegetable, and animal kingdoms, that exhibit such strong attractive affinities for one another, that, however much they may differ in their external appearances, and in their very natures, they are bound together by common bonds that connect them all into a single family; for we find the metal attaching itself to crystalline, animal, and vegetable substances; and, again, the crystal, whether we call it by the name of diamond, salt, or sugar-candy, connecting itself readily to metallic, animal, and vegetable bodies. In a similar way, animal bodies attach themselves to those that are mineral and vegetable; and, to complete the circle, the vegetable kingdom, by its woods, its gums, its lac, and its resins, is connected with them all.”

CHAPTER IX.

The electrical kite—Candles magically lighted—St. Elmo’s fire—The chronoscope—The electric clock—The electric telegraph—Sub-marine telegraphs—The overruling providence of God.