Question: Who invented the steam engine in the 1800s?

Disambiguated questions and answers:
context: The first full-scale working railway steam locomotive was built by Richard Trevithick in the United Kingdom and, on 21 February 1804, the world's first railway journey took place as Trevithick's unnamed steam locomotive hauled a train along the tramway from the Pen-y-darren ironworks, near Merthyr Tydfil to Abercynon in south Wales. The design incorporated a number of important innovations that included using high-pressure steam which reduced the weight of the engine and increased its efficiency. Trevithick visited the Newcastle area later in 1804 and the colliery railways in north-east England became the leading centre for experimentation and development of steam locomotives.
question: Who invented the first full-scale steam steam engine inside a working railway locomotive in the 1800s?
short_answers: Richard Trevithick

Trevithick
wikipage: Steam engine

context: No context provided
question: Who invented the horizontal steam engine in the 1800s?
short_answers: George Henry Corliss

context: Watt's patent prevented others from making high pressure and compound engines. Shortly after Watt's patent expired in 1800, Richard Trevithick and, separately, Oliver Evans in 1801 introduced engines using high-pressure steam; Trevithick obtained his high-pressure engine patent in 1802, and Evans had made several working models before then. These were much more powerful for a given cylinder size than previous engines and could be made small enough for transport applications. Thereafter, technological developments and improvements in manufacturing techniques (partly brought about by the adoption of the steam engine as a power source) resulted in the design of more efficient engines that could be smaller, faster, or more powerful, depending on the intended application.
question: Who invented the high pressure steam engine in the US independently of Trevithick?
short_answers: Oliver Evans
wikipage: Steam engine

Long answers:
knowledge: content: The Cornish engine was developed by Trevithick and others in the 1810s
wikipage: Steam engine

content: A Corliss steam engine (or Corliss engine) is a steam engine, fitted with rotary valves and with variable valve timing patented in 1849, invented by and named after the American engineer George Henry Corliss of Providence, Rhode Island.
wikipage: Steam engine

content: which was a four-valve counter flow engine with separate steam admission and exhaust valves and automatic variable steam cutoff.
wikipage: Steam engine

content: was a compound cycle engine that used high-pressure steam expansively, then condensed the low-pressure steam, making it relatively efficient. The Cornish engine had irregular motion and torque though the cycle, limiting it mainly to pumping. Cornish engines were used in mines and for water supply until the late 19th century.
wikipage: Steam engine

content:  In addition to using 30% less steam, it provided more uniform speed due to variable steam cut off, making it well suited to manufacturing, especially cotton spinning
wikipage: Steam engine
long_answer: In 1800, Richard Trevithick and, separately, Oliver Evans in 1801, introduced engines using high-pressure steam. Trevithick obtained his high-pressure engine patent in 1802, and Evans had made several working models before then. These were much more powerful for a given cylinder size than previous engines and could be made small enough for transport applications. On February 21, 1804, the world's first railway journey took place as Trevithick's unnamed steam locomotive hauled a train along the tramway from the Pen-y-darren ironworks, near Merthyr Tydfil to Abercynon in south Wales. The design incorporated a number of important innovations that included using high-pressure steam. This reduced the weight of the engine and increased its efficiency. Then, in the 1810s, the Cornish engine was developed by Trevithick and others. This was a compound cycle engine that used high-pressure steam expansively, then condensed the low-pressure steam, making it relatively efficient. The Cornish engine had irregular motion and torque though the cycle, limiting it mainly to pumping. Cornish engines were used in mines and for water supply until the late 19th century. In 1849, the Corliss steam engine was patented by American engineer George Henry Corliss of Providence, Rhode Island. This was a four-valve counter flow engine with separate steam admission and exhaust valves and automatic variable steam cutoff.  In addition to using 30% less steam, it provided more uniform speed due to variable steam cut off. These features made it well suited to manufacturing, especially cotton spinning.