HERO OF ALEXANDRIA. 



STEAM. 



Power of steam manifested by natural evaporation. 2. Early 

 attempts at its mechanical application Inventions of Watt. 3. 

 Influence of steam power on mankind. 4. Its agency in commerce 

 and the arts. 5. Analysis of its operation. 6. Combustion of 

 coals. 7. Force developed by the evaporation ot water. 8. Steam 

 an invisible aeriform fluid. 9. Measure of the mechanical force 

 developed. 10. Heat absorbed in evaporation. 11. Latent heat of 

 steam. 12. Effect of varying pressure. 13. Mechanical force 

 independent of the pressure 14. Force developed by expansion. 



LARDNER'S MUSEUM OF SCIENCE, 

 No. 48. 



193 



