Incumbents
- Monarch – George III
- Prime Minister – Henry Addington (Tory) (until 10 May), William Pitt the Younger (Tory) (starting 10 May)
- Foreign Secretary – Lord Hawkesbury (until 14 May) Dudley Ryder, 1st Earl of Harrowby (from 14 May)
| 1804 in the United Kingdom |
| Other years |
| 1802 | 1803 | 1804 | 1805 | 1806 |
| Constituent countries of the United Kingdom |
| England | Ireland | Scotland | Wales |
| Sport |
| 1804 English cricket season |
Events from the year 1804 in the United Kingdom.
1804 (MDCCCIV) was a leap year starting on Sunday of the Gregorian calendar and a leap year starting on Friday of the Julian calendar, the 1804th year of the Common Era (CE) and Anno Domini (AD) designations, the 804th year of the 2nd millennium, the 4th year of the 19th century, and the 5th year of the 1800s decade. As of the start of 1804, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923.
Richard Trevithick was a British inventor and mining engineer. The son of a mining captain, and born in the mining heartland of Cornwall, Trevithick was immersed in mining and engineering from an early age. He was an early pioneer of steam-powered road and rail transport, and his most significant contributions were the development of the first high-pressure steam engine and the first working railway steam locomotive. The world's first locomotive-hauled railway journey took place on 21 February 1804, when Trevithick's unnamed steam locomotive hauled a train along the tramway of the Penydarren Ironworks, in Merthyr Tydfil, Wales.
Merthyr Tydfil is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about 23 miles (37 km) north of Cardiff. Often called just Merthyr, it is said to be named after Tydfil, daughter of King Brychan of Brycheiniog, who according to legend was slain at Merthyr by pagans about 480 CE. Merthyr generally means "martyr" in modern Welsh, but here closer to the Latin martyrium: a place of worship built over a martyr's relics. Similar place names in south Wales are Merthyr Cynog, Merthyr Dyfan and Merthyr Mawr.
The Glamorganshire Canal in South Wales, UK, was begun in 1790. It ran along the valley of the River Taff from Merthyr Tydfil to the sea at Cardiff. The final section of canal was closed in 1951.
The year 1804 in science and technology involved some significant events, listed below.
The Taff Trail is a walking and cycle path that runs for 55 miles (89 km) between Cardiff Bay and Brecon in Wales. It is so named because it follows the course of the River Taff. Along much of its length, it follows the National Cycle Network Route 8 that continues to Holyhead, and is substantially off-road.
Events from the year 1831 in the United Kingdom.
Penydarren Ironworks was the fourth of the great ironworks established at Merthyr Tydfil in South Wales.
Pentrebach is a village in Merthyr Tydfil County Borough, Wales and is formed from the original settlements of Lower Pentrebach, Tai-bach and Duffryn.
The history of rail transport in Great Britain to 1830 covers the period up to the opening of the Liverpool and Manchester Railway, the world's first intercity passenger railway operated solely by steam locomotives. The earliest form of railways, horse-drawn wagonways, originated in Germany in the 16th century. Soon wagonways were also built in Britain. However, the first use of steam locomotives was in Wales. The invention of wrought iron rails, together with Richard Trevithick's pioneering steam locomotive meant that Britain had the first modern railways in the world.
Events from the year 1801 in the United Kingdom. The Acts of Union 1800 came into force this year.
Events from the year 1806 in the United Kingdom.
Pontygwaith is a village in the Taff Valley, 9 km south of Merthyr Tydfil in Wales.
Events from the year 1799 in Great Britain.
This article is about the particular significance of the year 1804 to Wales and its people.
Penydarren is a community and electoral ward in Merthyr Tydfil County Borough in Wales.
The Merthyr Tramroad was a 9.75-mile-long (15.69 km) line that opened in 1802, connecting the private lines belonging to the Dowlais and Penydarren Ironworks with the Glamorganshire Canal at Abercynon, also serving the Plymouth Ironworks along the way. Famous as the line on which Richard Trevithick's experimental locomotive hauled the first train to carry a load. It was largely superseded when the Taff Vale Railway opened in 1841 and sections gradually went out of use over the two decades from about 1851.
Merthyr Tydfil County Borough is located in the historic county of Glamorgan in Wales and takes its name from its largest town. The county borough covers an area of 111 km2 (43 sq mi) and had a population of approximately 58,900 in 2021. There are ten structures on the list of twelve Grade II* listed buildings in Merthyr Tydfil. Two viaducts constructed as part of the Brecon and Merthyr Railway both straddle the borders of neighbouring communities so have separate designations for each of these locations.
Events from the year 1804 in Scotland.