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 CHAPTER XXVII. HEATING APPARATUS--MARINE STEAM-ENGINES--REFORM COLUMN. Ill health, 1830--Hot-house boiler--Heating rooms--Discharging coal-ships by steam--Hot-water stoves for France--Patent for heating apparatus, 1831--Marine portable engines--Boat propeller--Wheal Towan--Discharging coal by steam at Hayle--Proposal to the Common Council of London--Every vessel to carry a steam-engine--Mr. George Rennie--Proposal to the Admiralty--Surface condensation--Locomotives supplying their own feed-water--Petition in Trevithick's favour--Davies Gilbert's suggestion--His comparison of the Watt and Trevithick engines--Maudslay on Trevithick's proposals--Patent of 1832--Superheating steam--Cylinder placed in flue from boiler--Expansive steam--Tubular boiler--Water propulsion--Superheating and surface condensation for locomotives--Detail of engine--Proposal to send steamboats to Buenos Ayres--Waterwitch Company--Messrs. Hall and Sons--Hall's condenser--Rennie and the Admiralty--'Syria' steamboat--Compound engines--Watt on high-pressure steam--Trevithick on compound engines--Tubular boiler and variable blast-pipe--Refusal of Trevithick's petition to Government--Ill health--Davies Gilbert's statement to Spring Rice--Meeting on proposed Reform Column--Trevithick's description--Means of ascent and descent--Placed before the King--Death--Funeral--His last letter Page 363-396