uantity of coal, not at all too
small in size. No flame was perceptible, although all the lamps were
carefully covered.

2. A 2 in. hole drilled 4 ft. 6 in. into the side of the coal about 10
in. from the top, fast ends not holed under, width of space 10 ft.
This was purposely a "blowout" shot. The result was again most
satisfactory, the charge exploding in perfect darkness.

3. A "breaking up" shot placed in the stone roof for "ripping," the
hole being drilled at an angle of 35 deg. or 40 deg. This is intended
to open a cavity in the perfectly smooth roof, the ripping being
continued by means of the "lip" thus formed. The charge was 105
grammes (nearly 4 oz), and it brought down large quantities of stone.

4. A "ripping" shot in the stone roof, hole 4 ft. 6 in. deep, width of
place 15 ft. with a "lip" of 2 ft. 6 in. This is a strong stone
"bind," and very difficult to get down. The trial was most successful,
a large heap of stone being brought down and more loosened.

5. A second "blowout" shot, under the conditions most likely to
produce an accident in a fiery mine. A 2 in. hole, 4 ft. 6 in. deep,
was drilled in the face of the coal near the roof, and charged with
105 grammes of roburite. A space of 6 in. or 8 in. was purposely left
between the charge and the tamping. The hole was then strongly tamped
for a distance of nearly 2 ft. The report was very loud, and a
trumpet-shaped orifice was formed at the mouth of the hole, but no
flame or spark could be perceived, nor was any inconvenience caused by
the fumes, even the instant after the explosion.

_Further Experiments at Wharncliffe Colliery._--On Tuesday, October
25, some very interesting surface trials were arranged with great care
by Mr. Walker. An old boiler flue was placed vertically, and closed at
top by means of a removable wooden cover, the interior space being
about 72 cubic feet. A temporary gasometer had been arranged at a
suitable distance by means of a paraffin cask having a capacity of 6
cubic feet suspended inside a larger cask, and by this means the
boiler was charged with a highly explosive mixture of gas and air in
the proportion of 1 to 12.

1. A charge of gunpowder was placed in the closed end of a piece of
gas pipe, and strongly tamped, so as to give the conditions most
unfavorable to the ignition of the firedamp. It was, however, ignited,
and a loud explosion produced, which blew off the wooden cover and
filled the boiler tube with flame.