l modifications of the safety-lamp, and the
merit of the discovery has been claimed by others, among whom was
Mr. George Stephenson; but the question was set at rest in 1817 by
an examination, attested by Sir Joseph Banks, P.R.S., Mr. Brande,
Mr. Hatchett, and Dr. Wollaston, and awarding the independent merit
to Davy.

It should be explained that Stephenson's lamp was formed on the
principle of admitting the fire-damp by narrow tubes, and "in such
small detached portions that it would be consumed by combustion."
The two lamps were doubtless distinct inventions; though Davy, in
all justice, appears to be entitled to precedence, not only in point
of date, but as regards the long chain of inductive reasoning
concerning the nature of flame by which his result was arrived at.

Meanwhile, the Report by the Parliamentary Committee "cannot admit
that the experiments (made with the lamp) have any tendency to
detract from the character of Sir Humphry Davy, or to disparage the
fair value placed by himself upon his invention. The improvements
are probably those which longer life and additional facts would have
induced him to contemplate as desirable, and of which, had he not
been the inventor, he might have become the patron."

"I value it," Davy used to say, with the kindliest exultation, "more
than anything I ever did; it was the result of a great deal of
investigation and labor; but if my directions be attended to, it
will save the lives of thousands of poor men."

The principle of the invention may be thus summed up: In the
safety-lamp, the mixture of the fire-damp and atmospheric air within
the cage of wire-gauze explodes upon coming in contact with the
flame; but the combustion cannot pass through the wire-gauze; and
being there imprisoned, cannot impart to the explosive atmosphere of
the mine any of its force. This effect has been attributed to the
cooling influence of the metal; but, since the wires may be brought
to a degree of heat but little below redness without igniting the
fire-damp, this does not appear to be the cause.

Professor Playfair has elegantly characterized the safety-lamp of
Davy as a present from philosophy to the arts, a discovery in no
degree the effect of accident or chance, but the result of patient
and enlightened research, and strongly exemplifying the great use of
an immediate and constant appeal to experiment. After characterizing
the invention as the _shutting-up in a net of the most slende