Graig Merthyr Colliery explosion, 1909

In the early hours of Friday 1 October 1909, as the night shift at Graig Merthyr Colliery in the Cwmdulais valley was about to leave, a pocket of gas exploded and killed five colliers and injured another. An open lamp was found at the face, and the Inspector thought the gas might have gathered in small coal lying on the floor, but he could offer no firm explanation. Three weeks later a fall of stone at the same colliery killed two more men.

Date	1 October 1909
Mine	Birchrock Colliery
Region	Swansea
Type	Explosion
Fatalities	5 (Arthur Schroeder, 41; Edward Mandry, Mandray or Mainwaring, 43, a married man of Felindre; John Whelan, 42, married, of Pontarddulais; David Rees, 36, married, of Felinfoel; Samuel Jones, 50, married, of Llanelli.)
Injuries	One man injured (NMRS).
Context	During active mining (The end of the night shift at the Graigola Merthyr Company's Birchrock or Graig Merthyr drift in the Cwmdulais valley, four months after a harmless explosion there.)

Cause

An explosion of a pocket of gas; the Inspector suspected gas accumulated in small coal on the floor, and an open lamp was found at the face.

Contributing factors

Gas had already exploded at the colliery that May without injury. An open lamp was found at the face after the explosion.

What happened

Graig Merthyr, the Graigola Merthyr Company's colliery in the Cwmdulais valley three miles from Pontarddulais, worked the Graigola seam near its outcrop and had been known as Birchrock until a few years before. Gas had exploded there on 26 May 1909 without hurting anyone. At 3.30 in the morning of Friday 1 October 1909, as the night shift was about to leave the pit, a pocket of gas exploded and killed five colliers: Arthur Schroeder, 41; Edward Mandry, 43 (Mandray in the Society's account, Mainwaring in the Welsh Coal Mines fatality list), a married man of Felindre; John Whelan, 42, married, of Pontarddulais; David Rees, 36, married, of Felinfoel; and Samuel Jones, 50, married, of Llanelli. One other man was injured. HM Inspector of Mines, Mr Dyer Lewis, could give no concrete theory of the cause. An open lamp had been found at the face, and on the floor lay a quantity of small coal; he knew that gas accumulated among small coal and thought it might have come from there. It was the first of two fatal explosions in the west of the coalfield within a few weeks, and the colliery had not finished with October: around midday on Thursday the 21st a huge stone fell from the side of a heading where a parting was being widened, killing Thomas Rees and trapping the brothers William and Thomas Richards, and a second stone killed Griffith Jeffreys, 33, who had come to their aid.

Investigation & inquiry

H.M. Inspector of Mines Dyer Lewis could give no concrete theory of the cause, but noted the open lamp at the face and the small coal on the floor, where he knew gas could accumulate.

What's uncertain

Points where sources disagree or the record could not be settled; both accounts are kept. All open questions in the archive.

The second man is Edward Mandry on the Welsh Coal Mines colliery page, Edward Mandray in the NMRS account, and Edward Mainwaring, a married man of Felindre, in Welsh Coal Mines' 1909 list. (disputed) ^1,2,3

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

An explosion of gas on 1 October 1909 killed five colliers: Arthur Schroeder, 41; Edward Mandry (or Mainwaring), 43; John Whelan, 42; David Rees, 36; and Samuel Jones, 50. ^1,2,3
The NMRS gives the time as 3.30 a.m., with one man injured; Welsh Coal Mines says the gas exploded just as the night shift was about to leave the pit. ^2,3
The second man is Edward Mandry on the Welsh Coal Mines colliery page, Edward Mandray in the NMRS account, and Edward Mainwaring, a married man of Felindre, in Welsh Coal Mines' 1909 list. (disputed) ^1,2,3
H.M. Inspector of Mines Dyer Lewis could offer no firm theory of the cause, but an open lamp was found at the face, and he thought gas may have gathered among small coal lying on the floor. ¹
An explosion of gas at the colliery on 26 May 1909 had injured no one. ³

Related terminology

Mining terms this disaster is structurally linked to, with the nature of the relationship.

Coal (contextual relationship)
Named 3 times in this record, first in the summary: “…face, and the Inspector thought the gas might have gathered in small coal lying on the floor, but he could offer no firm explanation. Three…”
Colliery (contextual relationship)
Named 3 times in this record, first in the summary: “…hours of Friday 1 October 1909, as the night shift at Graig Merthyr Colliery in the Cwmdulais valley was about to leave, a pocket of gas exploded…”
Firedamp (direct cause)
A pocket of gas exploded.
HM Chief Inspector of Mines (contextual relationship)
Named in this record’s investigation: “H.M. Inspector of Mines Dyer Lewis could give no concrete theory of the cause, but noted the…”
Naked Light (contributing factor)
An open lamp was found at the face.

Sources

(secondary) 1909 fatalities — Welsh Coal Mines
(secondary) Birchrock Colliery (Graig Merthyr) — Welsh Coal Mines
(secondary) Graig Merthyr Colliery — Northern Mine Research Society (information supplied by Ray Lawrence)

Record created: 14 September 2026 · Last researched: 16 September 2026