tions will be made before firing a
shot, thereby insuring greater safety. 8. In testing for gas with a safety
lamp there is a fear of the light being extinguished, when the lamp is
suddenly placed in a quantity of gas, or in endeavoring to get a very
small light; this is especially the case with some kinds of lamps. With the
detecter this is avoided, as a large flame can be used, which is considered
by some a preferable means of testing for small quantities; and the test
can be made without risk. Where gas is present in large quantities, the
blue flame at the end of the test tube will be found a further proof. This
latter result is produced by the slightest compression of the ball. (I need
not point out the inconvenience and loss of time in having to travel a mile
or more to relight.) As regards the use of the detecter with open lights,
several of the foregoing advantages or modifications of them will apply.
Instead of having to use the safety lamp as at present, it is thought that
the working place will be more frequently examined, for a sample of the
suspected atmosphere can be carried to a safe place and forced on to the
naked light, when, if gas be present, it simply burns at the end of the
mouthpiece like an ordinary gas jet. There are other advantages, such as
examining the return airways without exposing the lamp, etc., which will be
apparent, and become of more or less importance according to the conditions
under which the tests are made.

In conclusion, I wish to paint out that the practice adopted at some
collieries, of having all the men supplied with the most approved lamp
(such as the Mueseler or tin shield lamp) is not a safe one. If the
strength of a chain is only equal to the weakest link, it may be argued
that the safety of a mine is only equal to that of the most careless man or
most unsafe lamp in it. If, therefore, the deputies, whose duty it is to
look for gas and travel the most dangerous parts of the mine, are obliged
to use the Davy on account of its sensitiveness, may it not be said that,
as their lamps are exposed equally with the workmen's to the high
velocities of air, they are the weak links in the safety of the mine? For
the reasons given, I venture to submit that the difficulties and dangers I
have mentioned will be largely reduced, if not wholly overcome, by the use
of the fire-damp detecter.

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