Ventilation and Measurements of Air Current

The Coal Mines Act 1911 and attending regulations require the measurement each month, of the quantity of air in the main ventilation current to each seam, in every split in the current, where an intake road into a district forked off from the main intake road and at a point 100 yards back from the first working place at the face.

These measurements were required to be recorded in a book maintained in the mine for that purpose.

These sensible requirements were designed to ensure that adequate ventilation was provided throughout the workings and that it was duly recorded. The last measurements, prior to the explosion, of the air in various parts of the mine were recorded in December 20 th 1917 .

But, at the inquiry, it was established that the management contrived sections 24 (1) and 29 (2) of the Act. The manager’s explanation was, that these measurements were made by Jones; an overman, who was one of the victims of the explosion and were entered in his notebook, but not in the prescribed book.

As the notebook had not been recovered, the manager was unable to state the volume of air, which travelled the faces of the various districts and whether or not there was any undue leakage between the entrance to the ventilating districts and faces.

A further breach of section 62 (3) was recorded, by the failure to remove, as far as practicable, coal dust from the floor, roof and sides.

Mr. J.B. Atkinson, for 40 years H.M.I. of Mines, now consulting mining engineer representing the Miners Federation of Great Britain, stated at the inquiry:

“The roads traversed by the explosion contained an excess of coal dust”. And it was his opinion that, “this was the propagating agent”. Mr. Atkinson alleged that the Home Office had not taken proper measures to obviate the dangers arising from coal dust. He thought that they had been lacking in not drawing up proper regulations, and he also complained of their interference with Inspector’s reports. He resigned because of this.

There was further evidence when Mr. Cave of the North Staffs Miners Federation, called two witnesses. The first, Mr. George Harrison, of High St. Halmerend said he worked on the main level of the Bullhurst district for some weeks before the explosion, and these districts were very dusty. Formally, a man named Mainwaring was employed to clear up the dust, but he had left two or three months before, and, due to the men trampling though the dust, he said: “We could hardly see one an other when we were going out”. The second witness, Sam Bate, of high St. Halmerend, stated: “The main north level was six inches thick with dust. At weekends, lads cleared some of the dust away”.

Detailed plans, prepared with extraordinary care, showing the conditions in the pit after the explosion were put in and explained by Mr. Sethna, the colliery surveyor.

In addition a pit prop, thickly covered on one side by coked coal dust was produced. Mr. Biddington, the workman’s representative from Talke, said, the specimen prop was a fair sample from the bulk.

Having considered the dust aspect, let us look at the gas aspect, as these combined, only need a source of ignition to cause an explosion and both of the previous explosions, 1898 and 1915, were attributed to gob fires.

Gas and Shot Firing

In the working of the Banbury, Seven feet and Bullhurst seams, firedamp was given off freely. The manager, realising this, instructed his officials to withdraw the men when 2% or more gas was found in the working place and that a report was to be entered in the book kept for that purpose.

A breach of the 1911 Act section 14 (3) was recorded at the inquiry. A fireman had been assigned a district of such a size, that he was prevented from carrying out in a thorough manner all his statutory duties. H. Downing, in evidence stated that, when the manager assigned the district to him, he objected to taking it, on the grounds that it was too large. Then a shot-firerer was appointed to assist him in making the statutory inspections.

Evidence was given that shortly after midnight on January 11th the colliers in Ratcliffe’s place had come out owing to the presence of gas and sent for Rowley, who was described as assistant fireman and shotlighter. Rowley examined the place and found 1.5% of gas. He told the men to go back, but made no report because he considered that one was not required unless an official had withdrawn the workmen. After the inquiry it was recommended that a report be made if a workman had withdrawn himself.

In the Banbury seam, the fireman fired shots, as well as the shot firer, and, from the shot-firing book, there was evidence that those fired by the fireman, amounted at times to 40 per shift. The fireman, after being pressed by the Inspector, admitted more than two hours of the shift were taken up with the firing of shots. He estimated that each shot took him 3 minutes. But in cross-examination, he admitted it would take nearly 10 minutes. The practice followed in the Banbury seam was illegal.

All inspections in a fireman’s district, under sections 64-65 of the Act, must be made by the fireman in charge of that district, and if the fireman is allowed to fire any shots, the district assigned to him must be of such a size that shot firing does not interfere with his statutory duties. (Section 14)

Gas Explosion Coal Dust

As was mentioned earlier, the Minnie pit was a gassy pit, and Joe Johnson said, on the night before the explosion, he was working at the top of No4 district and during the night there was about 1.5% of gas in the place, which increased when tops came down in the adjacent Carter’s place.

Men working in Cartlidge’s place and Radcliffe’s, both at the top of No. 4 district, spoke of the presence of gas there on the night before the explosion.

Mr. Granville Pool, H.M.I. of Mines, was of the opinion that the point of origin of the explosion was in the gob at the top of No. 4 district, and the cause of ignition possibly, a damaged safety lamp, but more probably sparking from the Bulldog stone. As propagation or spread of explosion was concerned, he thought the first ignition was of gas and that this developed into a coal dust explosion, pure and simple.

Mr. Frank Lingard, who had worked as a miner in the Minnie pit for 26 years, describing the sparks he had seen in the mine, when Bulldog stone was breaking and falling from the roof, states:

“As near as I can tell you, it was like a tram going along, strikes one of the cups, it is like that only a longer streak, like an electric flash”.

Here were all the ingredients of a disastrous explosion of gas, a source of ignition, and coal dust.