488 NATURE'S TEACHINGS. 



the parallel will at once be visible. Just as the brain transmits 

 its message to the limbs by means of the nerves, so does the 

 same brain transmit its message through thousands of miles, 

 by utilising the wires which are but the rough and coarse imi- 

 tations of the wonderful nervous system of the human frame. 



THE illustration shows the parallelism as well as can be done 

 by a mere chart. 



On the left-hand side is shown the manner in which a nerve- 

 group is distributed to different parts of the body. On the 

 right the railway telegraph wires are seen, and, as the reader 

 will probably remember, branch wires are carried into the 



TELEGRAPHIC WIRES. 



signal boxes, just as branch nerves are carried to the most 

 distant parts of the body. 



I HAVE already mentioned the Electric Spark, and that it is, 

 in fact, a miniature lightning-flash, the little crackling report 

 being a miniature thunder-clap. It can be produced by fric- 

 tional electricity, or by the voltaic pile in its many variations, 

 or by animal substances alone, as in the case of the torpedo and 

 electric eel. 



We now come to a modification of the spark, whereby a con- 

 tinuous current of electricity is sent through two charcoal 

 points, and inflames them with such intensity that the eye can- 

 not look upon its dazzling whiteness. There is none of the 

 yellowness about it which is so great a drawback to our arti- 

 ficial lights, whether they be gas, candle, or lamp, and which 



