CHAPTER XXVI.

TUBULAR BOILER--SUPERHEATING STEAM--SURFACE CONDENSER.

Binner Downs engine, 1828--Fires around cylinder and steam-pipes--Saving of coal--Surface condensation at sea--Superheating tubes--Used steam returned to the boiler, 1828--Holland pumping engine--Woolf at the Consolidated Mines--Laws of steam--Power of heat from 1 lb. of coal--Loss of heat--Experiments at Binner Downs--Surface condensation--Partial surface condensation for ships or railways--Effect of superheating--Watt's theory doubted--Wheal Towan and other engines--Loss of heat--Injection-water--Surface condensation and superheating--Partial condensation engine--Duty of chain pumping engine--Surface condensation by cold water or air--Results of the experiment--Hayle Harbour--Condenser of copper tubes, 1829--Suitability for steam-ships--Proposal to erect at his own expense a marine engine with surface condenser and screw-propeller for the instruction of the Admiralty, 1830.--Sketch of tubular boiler and surface-air condenser--Screw draught--Preservation of heat in condensing by air--Comptroller of the Navy--Patent of 1831--Boiler within the condenser--Surface condensation by air or water--Safety boiler of concentric tubes--Blowing vessel for air condensation and draught--Tubes for distilling water--Steam pressure--Expansive working--Robert Stephenson's statement--'Echo' steamboat, 1831--Bottle-neck boiler--Admiralty--Steam Users' Association--Mr. Alexander Crichton's boiler and surface condenser--Captain Dick and Captain Andrew--Captain King and the 'Echo' Page 315-362