MAGNETIC EXPERIMENTS. 165 



Magnetic attraction will not be destroyed by interposing 

 obstacles between the magnet and iron. If you lay a small 

 needle on a piece of paper, and put a magnet under the pa- 

 per, the needle may be moved backwards and forwards ; and 

 with a piece of glass or board the effect will be the same. 

 This property of the magnet has afforded the means of seve- 

 ral amusing deceptions. A small figure of a man has been 

 made to spell a person's name. The hand, in which was a 

 piece of iron, rested on a board, under which a person, con- 

 cealed from view, with a powerful magnet, contrived to carry 

 it from letter to letter, until the word was made up. If the 

 figure of a fish, with a small magnet concealed in its mouth, 

 be thrown into the water, and a baited hook be suspended 

 near it, the magnet and iron by mutual attraction will bring 

 the fish to the bait. 



If you lay a sheet of paper, covered with iron filings upon 

 a table, with a small magnet among them, and then shake 

 the table a little, at the two ends or tl)e poles, the particles 

 of iron will form themselves into lines, a little sideways, 

 which bend, and then form complete arches, reaching from 

 some point in the northern half of the magnet to some other 

 point in the southern half. If you shake some iron-filings 

 through a gauze sieve upon a paper that covers a bar magnet, 

 they will be arranged in beautiful curves. 



Soft iron is attracted by the magnet more forcibly than 

 steel, but it is not capable of preserving the magnetic pro- 

 perty so long. The gradual addition of weight to a magnet 

 kept in its proper situation, increases the magnetic power, 

 but heat weakens it, and great heat destroys it. Bars of 

 iron that have stood long in a perpendicular situation, are 

 generally found to be magnetical ; this circumstance, toge- 

 ther with the phenomena of the compass and the dipping 

 needle, leaves no room to doubt but that the cause exists 

 within the earth. 



Questions. — 1. Where is the natural magnet found? 2. Why 

 are artificial magnets used in preference to natural ? 3. How may 

 very powerful magnets be formed ? 4. How do the poles of a mag- 

 net attract and repel each other ? 5. How does it appear that the at- 

 traction between the magnet and iron is mutual ? G. How does it 

 appear that magnetic attraction will not be destroyed by the interpo- 

 sition of bodies ? 7. What amusing deceptions has the attractive pro- 

 perty of the magnet afforded ? 8. How may the magnetic power be 

 weakened or destroyed ? 9, From what is it concluded that the cause 

 of magnetism exists in the earth .' 



