Editing Compound steam engine (section)

===Double-expansion===
*1833 – [[Hercules (1829 ship)|Hercules (1829)]] was modified to use an extra low pressure cylinder, taken from [[Agrippina (1827)|Agrippina]], with steam from her high-pressure cylinders. This modification was designed by Dutch engineer [[Gerhard Moritz Roentgen]],<ref>{{Cite journal |last=Löhnis |first=Th. P. |year=1916 |title=De Maatschappij voor scheeps- en werktuigbouw Fijenoord te Rotterdam, voorheen de Nederlandsche Stoomboot Maatschappij |url=https://www.delpher.nl/nl/tijdschriften/view?coll=dts&identifier=MMKB16:002468005:00001 |journal=Tijdschrift voor economische geographie |pages=137–138 |via=Delpher.nl}}</ref> making him the inventor of the naval compound steam engine. The steam paddle tugboat was then successfully used for service on the river [[Waal (river)|Waal]],<ref>{{Cite news |year=1834 |orig-date=August 29 |title=Ijzeren Spoorweg |pages=6 |work=Algemeen Handelsblad |url=https://www.delpher.nl/nl/kranten/view?coll=ddd&identifier=ddd:010069868:mpeg21:p006}}</ref> becoming the first ship with a compound steam engine to enter service.<ref>{{Cite book |last=Lintsen |first=H.W. |url=https://www.dbnl.org/tekst/lint011gesc05_01/index.php |title=Geschiedenis van de techniek in Nederland. De wording van een moderne samenleving 1800-1890. Deel V |year=1994 |language=Dutch}}</ref>
*1845 – [[William McNaught (Glasgow)|William McNaught]] devised a method of fixing an additional high-pressure cylinder within an existing beam engine. To do so involved using a long pipe to connect the cylinders, and an extra set of valves to balance them. In effect this acted as a receiving chest, and a new type of compound had been invented. This system allowed greater control of the steam intake and cut-offs. An engine could be slowed by either a throttle which reduced the pressure of the steam, or by adjusting the cut-off on either cylinder. The latter was more efficient as no power was lost. The cycle was smoother as the two cylinders were not in phase.{{sfnp|Hills|1989|p=157}}
*1865 – {{SS|Agamemnon|1865}} was launched, equipped with a 300[[Horsepower|hp]] compound steam engine. The engine was designed by [[Alfred Holt]], one of her owners. Holt had persuaded the [[Board of Trade]] to allow a boiler pressure of 60[[Pounds per square inch|psi]] instead of the normal 25[[Pounds per square inch|psi]] - a higher pressure was needed to realise the advantages of double-expansion. The efficiency obtained enabled this ship to travel 8,500 miles before [[coaling (ships)|coaling]]. This made her competitive on routes between China and Britain.<ref name="Clark" >{{cite book
  |last=Clark|first=Arthur H. |date= 1911|title=The Clipper Ship Era 1843-1869
  |url=https://archive.org/stream/cu31924020891416#page/n5/mode/2up
  |location=New York |publisher=G.P. Putnam Sons
  }}</ref><ref name="Greenwich" >National Maritime Museum, Greenwich, UK, http://collections.rmg.co.uk/collections/objects/66013.html</ref><ref name="Jarvis">{{cite book |last=Jarvis |first=Adrian |editor1-first=Robert |editor1-last= Gardiner |editor2-first=Dr Basil |editor2-last=Greenhill |date=1993 |title=The Advent of Steam – The Merchant Steamship before 1900 |publisher=Conway Maritime Press |pages=158–159 |chapter=9: Alfred Holt and the Compound Engine |isbn=0-85177-563-2}}</ref>