s; but the Davy was some years ago condemned, and is
now strictly prohibited in all Belgian and many English mines. Recent
experience, gained by repeated experiments with costly apparatus, has
resulted in not only proving the Davy and some other descriptions of lamps
to be unsafe, but some of our Government Inspectors and our most
experienced mining engineers go so far as to say that "no lamp in a strong
current of explosive gas is safe unless protected by a tin shield."

[Illustration]

If such is the case, Mr. Garforth seems to have struck the key-note when,
in the recent paper read before the Midland Institute of Mining and Civil
Engineers, and which we have now before us, he says: "It would seem from
the foregoing remarks that in any existing safety-lamp where one
qualification is increased another is proportionately reduced; so it is
doubtful whether all the necessary requirements of sensitiveness,
resistance to strong currents, satisfactory light, self-extinction, perfect
combustion, etc., can ever be combined in one lamp."

The nearest approach to Mr. Garforth's invention which we have ever heard
of is that of a workman at a colliery in the north of England, who, more
than twenty years ago, to avoid the trouble of getting to the highest part
of the roof, used a kind of air pump, seven or eight feet long, to extract
the gas from the breaks; and some five years ago Mr. Jones, of Ebbw Vale,
had a similar idea. It appears that these appliances were so cumbersome,
besides requiring too great length or height for most mines, and
necessitating the use of both hands, that they did not come into general
use. The ideas, however, are totally different, and the causes which have
most likely led to the invention of the ball and protected tube were
probably never thought of until recently; indeed, Mr. Garforth writes that
he has only learned about them since his paper was read before the Midland
Institute, and some weeks after his patent was taken out.

No one, says Mr. Garforth, in his paper read before the Midland Institute,
will, I presume, deny that the Davy is more sensitive than the tin shield
lamp, inasmuch as in the former the surrounding atmosphere or explosive
mixture has only one thickness of gauze to pass through, and that on a
level with the flame; while the latter has a number of small holes and two
or three thicknesses of gauze (according to the construction of the lamp),
which the gas must penetrate before it