THE STEAM-ENGINE. 



(FOURTH LECTURE.) 





Analysis of Coal. — Process of Combustion. — Heat evolved in it. — Form and Structure of Boiler. — 

 Wagon-Boiler — Furnace. — Method of Feeding it. — Combustion of Gas in Flues. — Williams's 

 Patent for Method of Consuming unburned Gases. — Construction of Grate and Ash-Pit. — Magni- 

 tude of Heating Surface of Boiler. — Steam-Space and Water-Space in Boiler. — Position of Flues. 

 — Method of Feeding Boiler. — Method of Indicating the Level of Water in Boiler. — Lever 

 Gauges.— Self-Regulating Feeders. — Steam-Gauge.— Barometer-Gauge.— Watt's Invention of 

 the Indicator. — Counter.— Safety- Valve.— Fusible Plugs.— Self-Regulating Damper.— Brunton's 

 Self- Regulating Furnace. — Gross and Useful Effect of an Engine. — Power and Duty of Engines. 

 — Horse-Power of Steam-Engines. — Table exhibiting the Mechanical Power of Water converted 

 into Steam at various Pressures. — Evaporation Proportional to Horse-Power. — Sources of Loss 

 of Power. — Absence of good Practical Rules for Power. — Common Rules followed by Engine- 

 Makers. — Duty distinguished from Power. — Duty of Boilers. — Proportion of Stroke to Diameter 

 of Cylinder. — Duty of Engines. — Cornish System of Inspection. — Table showing the Improve- 

 ment of Cornish Engines. — Beneficial Effects of Cornish Inspection. — Successive Improvements 

 on which the increased Duty of Engines depends, traced by John Taylor in his " Records of 

 Mining." 



