[2] In 1840, working began again, when John Edwards and his partner Magnes obtained a lease, which was transferred to W B Chorley from London later that year.

In the late 1850s, Chorley began to lose interest in the enterprise, and Searell moved on to the Hafon y Llan Quarry near Beddgelert.

This had an authorised capital of £100,000, and the company bought the Cwmorthin Isaf estate and part of Tanygrisiau village on 25 July 1861.

[5] At some point, the 1 ft 11+1⁄2 in (597 mm) Cwmorthin Tramway was constructed to connect the quarry with the nearby Ffestiniog Railway at Tanygrisiau.

It was mentioned in the 1850 edition of Cliffe's The Book of North Wales, and the Ffestiniog Railway accounts recorded the first passage of loaded slate wagons down the line in that year.

An existing siding at Tanygrisiau, which had served horse-drawn wagons from the quarry, was removed shortly afterwards.

Two rope-worked inclined planes allowed the tramway to negotiate the difference in level between the mill and the Ffestiniog Railway.

[4] The connection of the final incline to the railway was deemed to be dangerous by a Board of Trade inspector in 1864, as there were no trap points to prevent runaway wagons running onto the main line.

As a result, the Ffestiniog Railway had to install distant signals and a telegraph connection to the winding house at the incline summit.

Following a fatal accident in 1875, a test case was brought against them, and the enterprise was deemed to be a mine under the terms of the Act.

The waste tips eventually covered Cwmorthin Isaf farmhouse, and the company and some of its workers built houses in Dolrhedyn, just above Tanygrisiau.

Between 1876 and 1888, 132,866 tons of slate were shipped, but the burden of development was too great, and led to the winding up of the company in 1888.

[7] In 1882, the quarry employed over 500 men, and slates were produced in three mills, two of which were powered by water wheels and one by a steam engine.

Ultimately, the Welsh Slate Company lost the case, but rather than pay the compensation, they surrendered their lease, retaining their profits and quite a bit of their capital.

This upset the Oakeley Company, as he had been blamed by them for the Great Fall, and his attempts to recruit workers from the old quarry to come to Cwmorthin did not help the relationship.

They finished building the inclines to serve them, started after the 1884 Cwmorthin fall, and used steam engines to power them and the pumps needs to keep the workings dry.

The peak demand for slate had passed and with the industry descending into recession, it did not reach its reserve.

[7] The Oakeley Company had been concerned about the condition of the western end of their mine since 1889, as many of the pillars left between the chambers by the Cwmorthin workings were thinner than normal practice, and they feared another collapse, with the additional risk that the water from Llyn Cwmorthin might enter the workings, causing widespread flooding.

In 1902 Oakeley stripped Cwmorthin of its machinery and allowed the workings to flood, despite the advice of its own consulting engineer.

[18] Although there were supplies of good rock, work in Cwmorthin was hampered by the costs of transporting the finished slates, and by the lack of power.

Some local men worked it on a small scale, initially clearing the tunnels and getting rock from some of the falls.