Cheswick, Pennsylvania January 25, 1904 No. Killed - 179
From State Inspector's report, 1904, pp. xii, xiv
"I had not thought it possible that a catastrope so awful in proportions could occur in a mine like the Harwick.
which was new and reported to be relatively safe."
The explosion was of terrific force, the tipple, built of iron, was wrecked, and a mule was blown out and over the tipple from the bottom of the shaft.
The coal coal is mined by compressed-air machines of the Puncher type, blasted down by dynamite. The shots were prepared and charged by the men
who loaded the coal, and the shots were fired by shotfirers.
Each shot firer carried a Davy lamp; to fire, he inserted a wire through the gauze of the lamp until it was the proper temperature and would then apply
it to the fuse. The shots near the roof required an extremely heavy charge.
Nearly all advanced workings were very dry and dusty. Locked safety lamps were used exclusively in all working places, except at the bottom of the shaft.
The cause of this explosion at about 8:15 a.m. was a blown-out shot in a part of the mine not ventilated as required by law.
Sprinkling and laying of the dust had been neglected; firedamp existed in a large portion of the advanced workings.
The explosion could be transmitted by the coal dust suspended in the atmosphere by the concussion from the initial explosion, the flame exploding
the accumulations of firedamp and dust along the path of the explosion, carry death and destruction into every region of the workings.
The fireboss did examine part of the mine. His last report was made January 23.
Insufficiency of ventilation was partly due to accumulation of ice at the airshaft.
Historical Summary of Mine Disasters in the United States - Volume I