In June 1790 an Act of Parliament was passed, allowing the construction of the Glamorgan Canal “from a place called Merthyr Tydvil …… to and through a place called the Bank, near the town of Cardiff”.
It had taken a long time to get this Act through – for years the ironmasters of Merthyr had found great problems in getting their iron down to the sea, and had been trying to find a better way.
The iron had originally been carried on the backs of mules and horses over the mountains from Merthyr to Cardiff. Each animal could only carry about a hundredweight, and a woman or boy walked a string of three or four over the trackways for 25 miles.
In 1767, funds were raised for the construction of a road between Merthyr and Cardiff, and for the next 25 years the iron was carried in wagons drawn by horses, which had to be changed at intervals along the road. The wagons had to pay tolls which varied according to the size of the wagon and the type of load carried.
The route of the canal was a very difficult journey. Merthyr is very much higher than Cardiff, and there are several very steep bits along the way. So that meant that there would have to be a number of locks to lower the level of the water where necessary.
In the one mile between Quakers Yard and Abercynon there were 16 locks, 11 of them in only a quarter of a mile. By the time a boat reached Tongwynlais, it had passed through 41 locks. But with all this to build, the canal was completed in 3 ½ years. It was 25 miles long, had 50 locks and an aqueduct, and was later extended from the town wall in Cardiff down to the shore.
One of these locks near the former junction of the Aberdare Canal is still in place and the stonework has been repaired to its former glory by the owner of Plymouth House in whose grounds it stands.
Many businesses grew up alongside the canal, including the famous Nantgarw Pottery, and very many of the people in the villages along the way were employed either on the canal or because of it.
There were a set of locks at Abercynon which opened directly into one another and were known as staircase locks. In very steep spots this was the only way to manage the canal, and there was another staircase later at Taffs Well.
Soon after, the canal went through another lock, this time at Forest Farm, near Whitchurch, and then it was only a short distance to the famous Melingriffith works at Whitchurch, which were connected closely with the Cyfarthfa iron works. The proprietor of Melingriffith was the treasurer of the canal company and iron from Cyfarthfa and from Pentyrch iron works was carried down the canal to be made into tinplate.
In 1800 the MG tinplate works were reputed to be the largest tinplate works in the world! The canal was important to them for bringing iron down from Merthyr to be processed, and for shipping their goods down to Cardiff for export.
In the 1970s the A470 dual carriageway from Cardiff to Merthyr was constructed and followed the route of the canal almost totally so destroying just about all the remains of the canal.