SUMMARY. 283 



that of a man feeding the furnace with coals. Look at any 

 one of your own clothes, at the ironwork in all parts of your 

 house, from the rough heavy iron of fireplaces and fenders 

 to the delicate steel spring which moves the hands of your 

 watch ; look at the planks on your floors, and the carpets 

 which cover them ! All these have been woven, and forged, 

 tempered, sawn, and worked by steam machinery. Then 

 think of the way in which people are carried from one place 

 to another of the world ; so that in one month a man may 

 be in India, and the next in London ] while food, clothing,' 

 and goods of all kinds are spread over different countries in 

 a few weeks whenever they are wanted. And then remem- 

 ber that all this has sprung out of the latent heat of steam, 

 and its application by Watt to the steam-engine. 



The next discovery is perhaps even more wonderful. 

 Franklin tries experiments upon the peculiar power known 

 by the name of electricity ^ and he suspects that it is every- 

 where and in everything. He proves its passage from one 

 body to another, and finds out many of its properties. In 

 spite of the derision of his friends, he seeks to bring it 

 down from the sky, and succeeds in making a prisoner of the 

 lightning and working with it in his own laboratory. Galvani 

 next finds this wonderful power hidden in the nerves of a 

 frog ; while Volta crowns the whole by showing how power- 

 ful electricity can be produced by two metals placed in a 

 little acid and water, and how this can be carried along 

 a wire of any length which touches the battery at both its 

 ends. Here lies hid the germ of the electric telegraph ; but 

 the grand secret of carrying messages from one end of the 

 world to another in a few moments was not to come yet. 

 That remained for the nineteenth century to accomplish. 



Astronomy. — Lastly we come to astronomy, and to some 



