STEAM. 



15. Force developed by condensation. 16. Application of these 

 three forces in steam engines. 17. Steam may act variously on 

 piston. 18. Furnaces and boilers. 19. Evaporating power of fuel 

 20. Means of economising heat. 21. Prevention of loss by 

 radiation. 22. Inspection and reports of Cornish engines. 23. 

 Greatly improved efficiency. 24. Actual mechanical virtue of coals. 

 25. Illustrations Pyramids of Egypt. 26. Menai Bridge. 27. 

 Railway engines. 28. Exhaustion of coal mines improbable. 29. 

 Prospects of scientific discovery. 



1. THE surface of the globe has been inhabited by the human race 

 for at least fifty or sixty centuries. During that long period their 

 intelligence has been as acute, their interests as exigent, and their 

 craving for material good, as insatiable as at present ; yet a natural 

 agent of vast power which existed around them, below them, and 

 above them, whose ' play was incessant in the air, upon the earth, 

 and in the waters under the earth, remained unobserved and 

 undiscovered until the last century; its powers were imper- 

 fectly developed until late in the present century, and its still 

 undeveloped consequences and effects, affecting the well-being and 

 progress, physical, moral, and intellectual, of the whole human 

 race, are such as the most acute and far-sighted cannot foresee. 

 This giant power is STEAM. 



Since the day on which the land was divided from the waters by 

 the Word of the Most High, evaporation, that is the conversion of 

 water into steam, and condensation, that is the reconversion of 

 steam into water, have been incessantly in operation upon a vast 

 scale, and a corresponding amount of mechanical force has been 

 developed and manifested on every part of the globe. By the 

 solar heat, the waters of the ocean have been constantly vaporised 

 and taken up into the higher regions of the air. Assuming there 

 the form of clouds, they have been attracted by the mountains, 

 and the more elevated parts of the land. There condensation 

 has taken place, and the vapour has been re-converted into 

 water, or even reduced by still greater cold to the solid state, 

 and has been precipitated in the form of rain, hail, or snow, 

 more or less, on all parts of the land, but chiefly, and most 

 abundantly, on the summits of mountain chains, and on the 

 more elevated regions. Descending from thence along the sur- 

 face, they form the streams of rivers, and the torrents of 

 cataracts, manifesting everywhere vast mechanical force, of which 

 man has eagerly availed himself, without reflecting on its origin, 

 or being conscious that he was using the indirect power of steam. 

 By the force exhibited in the flow of rivers, transport from the 

 interior of continents to their coasts has been effected since the 

 earliest times, and among people the least advanced in the arts of 

 life. By the force of cataracts, mills have been worked even in 

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