of the subsequent shots, with the same weight of roburite, produced
from 10 to 11 tons of coal in almost a solid mass.

It has been found that a fertile cause of accidents in coal mines is
insufficient tamping, or "stemming," as it is called in Yorkshire.
Therefore a hole was bored into a strong wall of coal, and a charge of
45 grammes inserted, and very slightly tamped, with the view of
producing a flame if such were possible. This "blowout" shot is so
termed from the fact of its being easier for the explosion to blow out
the tamping, like the shot from a gun, than to split or displace the
coal. The result was most successful, as there was no flash to relieve
the utter darkness.

The second set of experiments took place on October 24 last, in the
Monk Bretton colliery, near Barnsley, of which Mr. W. Pepper, of
Leeds, is owner. This gentleman determined to give the new explosive a
fair and exhaustive trial, and the following programme was carried out
in the presence of a very large gathering of gentlemen interested in
coal mining. The chief inspector of mines for Yorkshire and
Lincolnshire, Mr. F.N. Wardell, was also present, and the Roburite
Explosives Company was represented by Lieut.-General Sir John Stokes,
K.C.B., R.E., chairman, and several of the directors.

1. _Surface Experiments._--A shot fired on the ground, exposed. This
gave no perceptible flame (70 grammes of roburite was the charge in
these experiments).

2. A shot fired on the ground, bedded in fine coal dust. No flame nor
ignition of the coal dust was perceptible.