Part of the summary from the official Inquiry Report for “Blantyre Colliery Explosion” of 1877. Transcribed by myself word for word for the first time appearing online, this particular detailed section summarises the causes. I hope there are those people out there interested enough in this level of detail:
“Having apparently gas likely to have been in existence sufficient to account for the explosion, it might be supposed needless to look for more. It was alleged, however by some, that had the ventilation been in the state described, the explosion would probably have happened sooner. Exceptional circumstances were therefore surmised. These consisted of the possibility of an outcome of gas, escape of air such as might occur from leaving open of a trap door, the fall of roof in an airway, and increase of gas from a falling barometer.
“As to an outcome or outburst of gas or escape of air there was no direct evidence. As to the stoppage of an air course by a fall of rood, one such fall which would have caused this was found after the explosion. It deserved and received careful consideration. It was one amongst several other falls. No markings by dust or otherwise were noticed to distinguish one fall from another. Most of the other falls were where men must have travelled on the morning of the explosion, and which had no doubt been caused by the force of the explosion. The one selected was in the main intake airway between No3 and 2 pits, near where the explosion had been most violent. It was not in any ordinary working or travelling road, but it was where the firemen travelled.
“The surviving night fireman of No 2 pit states that he passed through that airway at 3 o’clock on the morning of the explosion, and there was then no fall nor any dribbling or other indication of the roof being likely to fall. Neither did he detect any falling off in quantity of air whilst he remained in the pit, viz, until 6am. The day fireman, Watt, if he did his duty, would that morning between 4.30 and 5.20am have passed through that place. Between then and 8.45am, the time of the explosion, the miners were in parts of the mine that would have been affected had there been an interruption in the ventilation. There was free course to No.2 shaft from one side of the fall, and to No. 3 from the other side, but no person came or sent any alarm. The oversman and two firemen came out of No.3 shaft together just before the explosion. He and the firemen say they found the air as usual. “
“One difference between this fall and some others may be stated for what it is worth. Most of the others occurred where the roof had been supported by timber. One fall in Spears dook, where the blast had been very severe, was not at a timbered part, but a brick stopping close to it had been blown out, which may have previously given support. The fall in the airway was near where a wood stopping had blown out. The ordinary wood stoppings had three upright props to which the boards were fastened, but was suggested that these uprights might not in this particular instance have given enough support, and that the fall may have come down before and not after the explosion.”
“As to a fall in the barometer, the subject was named by two witnesses, but neither of them had definite information to offer. One of them stated that the barometer was almost constantly on the move, and that there was no reason that he knew why this colliery more than others should have been affected. Atmospheric changes, however doubtless do produce some effect, although they are apparently often set forth as an excuse for inadequate ventilation. The question, therefore, seems appropriate for consideration. The weather chart published in the ‘Times’ for Monday, October 22nd 6pm, the day of the explosion, shows that over the south of England the barometer was 29.8 inches and 29.4 inches over the part of Scotland in question. The same paper shows that at Kew, the barometer fell about a quarter of an inch on the preceding day, but was nearly steady at the time of the explosion. At Derby, according to Mr. Davis’s published chart, the barometer fell quickly until about the time of the explosion. “
“At Manchester according to Mr. Casartelh’s hourly barograph, it fell until the afternoon of the previous day, and then slightly rose until the time of the explosion. A reading at Auchinarith, close to Blantyre shows that on the preceding Saturday, the height was 29.76 inches and on the Monday 29.19 inches, but there being no reading for the Sunday it was now shown when the fall took place. At the Observatory, Glasgow, the hourly measures derived from the barographic and thermographic records (with a copy of which through the kindness of Professor Grant), we have been favoured were remarkably steady. The barometer varied only 0.120 of an inch during the 24 hours preceding the explosion, the variations in the height being between 29.264 and 29.144 inches, the fall between 8 o’clock and 9 o’clock (the explosion being at 8.45am) bring only 0.022, which no colliery manager would think worthy of notice. The thermometer at the time of the explosion was at 52 degrees, being within one degree of what it was at the same hour on the previous day, the fluctuation in the interval having been only about 6 degrees. The reading at Derby shows that the greatest depression occurred in the part of the kingdom, and therefore that gas should have issued there, and not in the part of Scotland where the barometer was nearly steady. None of the readings show any storm curve. Indeed, there seems nothing in this respect which could have injuriously affected any mine, unless the margin of surplus ventilation had been run dangerously close.”
“Boisterous winds, which baffle the provisions for ventilation, occasionally produce worse effects than any fall in the barometer, especially in shallow pit, but nothing of the kind was shown to have been in existence.
“The most important effect produced in mines by atmospheric causes is apparently occasioned when by the sinking of a new shaft or the making of a borehole, or the cutting of a fault, atmospheric pressure is brought to bear and gas is thus liberated from the strata, especially into mines on the rise.
“An instance of this is given in the Reports of the Inspectors of Mines, for the year 1855 (Mr Dickinson’s). A pit called the Whins Pitt, only 14 yards deep, was sunk on to a level going in from the outcrop of the coal, close to where coal for the supply of two farmhouses had been worked at intervals during at least 30 years, and is supposed to have been worked for 100 years without any indication of firedamp having ever been seen. On the occasion in question, when the pit was about to be entered after an interval of three of four months, an explosion took place, killing one person and injuring two others; and on Mr Dickinson visiting the place to ascertain the cause, he found firedamp pouring out both at the top of the shaft and at the level mouth. That firedamp he then attributed to the sinking of two shafts to the same coal on the drip, at Hapton Valley, 1,600 yards off. He then surmised that no fault of sufficient magnitude intervened to stop the free flow of gas upwards by its lighter gravity. This has since been proved to be the case.
At Blantyre, so far as could be ascertained, and Mr. Duncan made inquiry on the subject, no such atmospheric cause could be in operation, the only new pit in the neighbourhood being, as stated by Mr. Moore, the Government Inspector for the district, separated by a dyke. The gas to be dealt with on the day of the explosion may, therefore, in this respect be considered as the normal quantity.”
AI illustrated by imagining the instruments being checked during the inquiry.