The explosion, although limited as regards loss of life and area of the mine affected, yet possesses special features of interest in being caused by flame from a Permitted Explosive and as presenting some difficulty in determining the relative influence of firedamp and coal dust.

The explosion was confined to a small district where the ordinary complement of workmen included three hewers in each shift, a pony putter and two drivers. It was twice inspected daily by the deputy in the fore shift and once by the deputy in the back shift. When workmen were employed in it during the night shift further inspections were made.

The plan on Plate I. on a scale of 8 chains to an inch shows the workings in the district, together with the roads connecting them with the downcast and upcast shafts. The plan on Plate II. on the scale of 5 chains to 3 inches shows the workings over which the explosion extended.

A hand sketch, Plate III., illustrates the point of origin of the explosion.

The Busty seam at the downcast shaft lies at a depth of 113½ fathoms. In the district of the explosion the seam lies one fathom below its level at the shaft and about 107 fathoms from the surface.

The general dip of the strata is to the east and is modified by faults having throws up to 5 or 6 fathoms.

The section of the seam at the downcast shaft is as follows :—

Two sections of the seam in the 1st South district are shown on the large scale plan, from which it will be seen that the section is variable.

The working places in the 1st South district consisted of three roads with the connections necessary for the purposes of ventilation and haulage. As the plan shows, these roads had been first driven in a south-easterly direction and were called crosscuts, and then turned to the south and were called headways.

They were driven with the bend in order to avoid passing through some small interlying royalties and were intended to win an area of coal beyond, known to be of good workable section.

The crosscuts were first driven in the Busty seam and then passed from that seam at a downthrow fault and were driven for about 279 yards in an upper seam called the Towneley seam, but which is probably the Hodge or Tilley seam of Tyneside, and which lies between the Busty and Towneley seams. A rise fault further in brought the Busty seam up to about its former level, and the inner part of the crosscuts and the headways were driven in that seam.

The seam called the Towneley seam has the section shown on the large scale plan.

All the passages, both crosscuts, headways, and the connecting passages called stentons, were driven about 8 feet wide with the exception of the middle crosscut and headway, which were 10 feet wide. The passages near the face were fairly level, but a stenton occupied by a hewer named Suggett on the day of the explosion, had a rise of about 2 inches per yard to the face.

The method of working the places with the section of seam as existing at the face at the time of the explosion was as follows

The coal was holed or kyrved right across the face to a depth of 3½ feet in the lower part of the seam, then two machine drilled holes of 1½ inches gauge and about 3½ feet deep were put in on each side about the top of the bands and fired in succession. Then two similar holes were drilled in the top coal and also fired in succession.

Westfalite No. 2, with No. 7 detonators, was the explosive used, and all the shots were fired by the deputies with an electric battery.

In the lower holes the usual charge was 8 oz. In the top holes the quantity was less, 5 oz. or 6 oz. Clay was provided by the owners for stemming the holes, which the deputy both charged and stemmed.

Westfalite No. 2 is described as follows in the Explosives in Coal Mines Order, dated the 24th April, 1903, and is of the same composition as that described in the most recent Order, dated the 17th December, 1906 :—

Westfalite No. 2, consisting of the following mixture :—

As far as possible the hewers separated the thin coal from the bands and filled the coal into tubs. The bands themselves were built up by the side of the roads or sent outbye.

The coal was filled at the face into iron tubs of good construction carrying 10 cwts., the pony putter led the tubs singly to the flat, whence they were taken by the drivers in sets of two to the endless rope road.

The ventilation of the whole colliery is produced by a Waddle fan 35 feet in diameter, and ordinarily running at 60 revolutions per minute with a water gauge of 246 inches.

At the week ends the fan was reduced in speed from 60 revolutions to from 50 to 55 revolutions. At 3 p.m. on Sundays it was put up to the ordinary speed.

The 1st South district was ventilated by a split of air which, when last measured on 5th December, 1906, at the regulator for the district — shown by the letter R on the small scale plan — amounted to 12,555 cubic feet per minute.

The regulator consisted of a wooden frame 3½ feet square set in brickwork, with a sliding door, which could be adjusted so as to partially close the area. This door at the time of the explosion was so placed as to leave an area of 3½ feet by 13 inches.

The current of air after leaving the endless rope road extending from the shaft in a westerly direction, passed inbye by the 1st South driving road which, with the middle crosscut and the middle headway, was eventually to be made an endless rope road and would then be the main intake over the whole length; but in the meantime the air left this road before reaching the crosscuts and passed through some old pillars along a temporary driving road by the route shown on the plan ; the main current then passed along the left-hand crosscut and left-hand headway to the face, but a portion was allowed to pass down the middle crosscut, joining the main current at the left-hand headway, the united current then passing to the face and round the working places, which were all closely bratticed up, and so by the right-hand headway and right-hand crosscut to the main return.

A few of the openings nearest the shafts between the middle and right hand crosscut were closed by brick stoppings, but beyond and in the headways the openings were closed by being stowed with band and supplemented by canvas stoppings, and probably a considerable part of the 12,555 cubic feet of air per minute entering the district would pass from the intakes to the return without reaching the face.

No light other than a locked safety lamp was allowed in the district. The lamps used are Marsaut's, locked by means of a lead plug, and tested in the lamp-room on the surface in a mixture of lighting gas and air passing over the lamp with some velocity induced by a small steam driven fan.

The coal and enclosing strata in the 1st South district are charged with firedamp, which can be heard hissing from the face when it is wet or damp, and can be both seen and heard bubbling up through water where it stood in pools on the floor. The air current required to be carried by bratticing close to the face of all the working places. The gas came off as a regular flow and no sudden outbursts had occurred, but in some cases the ordinary issue had been more than the air current could dilute, and occasionally some of the places had not been worked in consequence.