264 FRAGMENTS OF SCIENCE. 



knowledge of facts from actual observation. Facts looked 

 at directly are vital; when they pass into words half the 

 sap is taken out of them. You wish, for example, to get 

 a knowledge of magnetism; well, provide yourself with a 

 good book on the subject, if you can, but do not be con- 

 tent with what the book tells you; do not be satisfied with 

 its descriptive woodcuts; see the operations of the force 

 yourself. Half of our book writers describe experiments 

 which they never made, and their descriptions often lack 

 both force and truth; but no matter how clever or con- 

 scientious they maybe, their written words cannot supply 

 the place of actual observation. Every fact has numerous 

 radiations, which are shorn off by the man who describes 

 it. Go, then, to a philosophical instrument maker, and 

 give a shilling or half a crown fora straight bar-magnet, or, 

 if you can afford it, purchase a pair of them; or get a 

 smith to cut a length of ten inches from a bar of steel an. 

 inch wide and half an inch thick; file its ends smoothly, 

 harden it, and get somebody like myself to magnetize it. 

 Procure some darning needles, and also a little unspun 

 silk, which will give you a suspending fiber void of torsion. 

 Make a little loop of paper, or of wire, and attach your 

 fiber to it. Do it neatly. In the loop place a darning- 

 needle, and bring the two ends or poles, as they are called, of 

 your bar-magnet successively up to the ends of the needle. 

 Both the poles, you find, attract both ends of the needle. 

 Replace the needle by a bit of annealed iron wire; the 

 same effects ensue. Suspend successively little rods of 

 lead, copper, silver, brass, wood, glass, ivory, or whale- 

 bone; the magnet produces no sensible effect upon any of 

 the substances. You thence infer a special property in 

 the case of steel and iron. Multiply your experiments, 

 however, and yon will find that some other substances, 

 besides iron and steel, are acted upon by your magnet. A 

 rod of the metal nickel, or of the metal cobalt, from which 

 the blue color used by painters is derived, exhibits powers 

 similar to those observed with the iron and steel. 



In studying the character of the force you may, however, 

 confine yourself to iron and steel, which are always at hand. 

 Make your experiments with the darning-needle over and 

 over again; operate on both ends of the needle; try both 

 ends of the magnet. Do not think the work dull; you are 

 conversing with Nature, and must acquire over her Ian- 



