CHAP. xv. COMPARISON WITH OTHER CENTURIES. 151 



3. Electric Telegraphs, which have produced an even 

 greater revolution in the communication of thought. 



4. The Telephone, which transmits, or rather repro- 

 duces, the voice of the speaker at a distance. 



5. Friction Matches, which have revolutionized the 

 modes of obtaining fire. 



6. Gas-lighting, which enormously improved outdoor 

 and other illumination. 



7. Electric-lighting, another advance, now threaten- 

 ing to supersede gas. 



8. Photography, an art which is to the external forms 

 of nature what printing is to thought. 



9. The Phonograph, which preserves and reproduces 

 sounds as photography preserves and reproduces forms. 



10. The Rontgen Rays, which render many opaque 

 objects transparent, and open up a new world to 

 photography. 



11. Spectrum Analysis, which so greatly extends our 

 knowledge of the universe that by its assistance we are 

 able to ascertain the relative heat and chemical consti- 

 tution of the stars, and ascertain the existence, and meas- 

 ure the rate of motion, of stellar bodies which are en- 

 tirely invisible. 



12. The use of Anaesthetics, rendering the most se- 

 vere surgical operations painless. 



13. The use of Antiseptics in surgical operations, 

 which has still further extended the means of saving life. 



Now, if we ask what inventions comparable with these 

 were made during the previous (eighteenth) century, it 

 seems at first doubtful whether there were any. But 

 we may perhaps admit the development of the steam- 

 engine from the rude but still useful machine of New- 



