SAFETY 
536 
to his discovery. Oil this point his account was so clear and 
so consonant with the laws of human invention, that no one 
could refuse it the most implicit belief. The result was a 
perfect conviction on the minds of the gentlemen concerned, 
that Mr. Stephenson was the first inventor of a safety-lamp, 
and he accordingly received in acknowledgment thereof a 
piece of plate of seven or eight hundred pounds value. 
It cannot be supposed that we should here enter upon the 
above evidence. Those who are sceptical as to the accuracy 
of our statement, may consult a Report upon the Claims of 
Mr. George Stephenson relative to the Invention of his 
Safety-Lamp, by the Committee appointed at a Meeting 
holden at Newcastle, with an Appendix, containing the 
Evidence. Baldwin, 1817. 
We shall now proceed to lay before our readers the steps 
of this invention; first, as it took place with Stephenson; 
secondly, as it was proceeded in by Sir H. Davy. 
Stephenson informs us, that about the month of August, 
1815, he was in the habit of making experiments upon 
blowers; found that when blowers were lighted, and a 
number of lighted candles, viz. four, five, or six, held to the 
windward of the lighted blowers, the blowers were put out 
“ by the burnt air (as he conceived) which was carried 
towards them.” Mentioned this to several workmen. 
Hence, he conceived, that if a lamp could be made to con¬ 
tain the burnt air above the flame, and to permit the fire¬ 
damp to come in below in a small quantity, to be burnt as it 
came in, the burnt air would prevent the passing of explosion 
upwards, and the.velocity of the current from below would 
also prevent it passing downwards. In consequence, a few 
weeks after this idea entered his mind, he ordered a lamp 
furnished with air by means of a tube at its under surface, 
and having small perforations on its upper surface. As it 
was essential to his theory that the air passing out at the 
superior apertures should be incapable of supporting combus¬ 
tion, he resolved to admit through his lower tube no more air 
than wasabsolutely necessary for the-combustion of the wick. 
For this purpose he placed a slide on this lower opening. 1 
The following description of the annexed plate renders 
this invention very clear:— ' 
Fig. 1.—A. B. C. D. the lamp made of tin.—G. the glass 
cylinder.—A. E. F. D. the top which takes off 1 to admit the 
glass cylinder, and keeps it tight to the bottom B. C.—H. 
two tin tubes, the cavity between them for the wick; the 
interior one to admit the air..—I. the chamber for the oil. 
Fig. 2.—K. the bottom of the lamp with the slide P. to 
regulate the quantity of air to be admitted. 
Now this lamp was carried into several explosive mixtures, 
was put out and relit many times, but it did not burn very 
well, and was extinguished by being carried fast. At the 
period we are now speaking of, it must be confessed, that 
Steplienson had not discovered the fact, that explosion of 
hydrogen gas cannot take place through tubes of certain 
dimensions, under any circumstances, (if this be really the 
case); but that he thought this effect was produced by the cur¬ 
rent of explosive air being directed inwards from below, while 
it was rendered non-explosive before it passed out above. 
It is remarkable that Sir H. Davy adopted this explanation 
so late as January, 1816, even after he had invented his wire- 
gauze lamp, to which, in our Opinion, it is not applicable. 
He says, “ Taking all these circumstances into account, there 
appears no difficulty in explaining the combustion of explosive 
mixtures within and not without the cylinders; for a current 
is established from below upwards, and the hottest part of 
the cylinder is where the results of combustion, the water, 
carbonic acid, or azote, which are not inflammable, pass out. 
The gas which enters is not sufficiently heated on the outside 
of the wire, to be exploded, and as the gases are no where 
confined, there can be no mechanical force pressing currents 
of flame towards the same point.” 
Mr. Stephenson’s second lamp we shall pass over, and 
proceed to describe his third and last improvement. See 
figures 3 and 4 of the plate. 
Fig. 3.—A. B. C. D. the lamp.—A. E. F, D. the cover for 
L A M P. 
the top.—G. the tube for supplying the oil.—H. the wire to 
trim the wick.—I. the perforated plate covering the air cham- 
ber which surrounds the oil vessel.—K. L. apertures through 
which the air passes into the air chamber.—M. the tube for 
the wick. 
Fig. 4.—N. O. P. Q. the cover to protect the glass cylin¬ 
der. These figures represent the lamp at present in Killing- 
worth Colliery. 
' Sir H. Davy, on the 9th of September, read to the Royal 
Society, a paper in winch he gave the following account of 
the coal-damp, and of the means of preventing its dan¬ 
gerous explosion. 
“ Inflammable gas is disengaged from fresh coal, but the 
great sources of the fire-damp in mines are, however, what 
are called blowers, or fissures in the broken strata, near 
dykes, from which currents of fire-damp issue in considerable 
quantity, and sometimes for a long course of years; and 
the deeper the mine the more common in general is this 
substance.” 
Of six specimens collected from a blower in the Hebburn 
Colliery, by emptying bottles of water close to it, the purest 
contained only of atmospherical air, with no other con¬ 
tamination, and the most impure contained of atmo¬ 
spherical air: so that this air was probably derived from the 
circumambient air of the mine. The weight of the purest 
specimen was for 100 cubical inches 19.5 grains. 
One measure of it required for its complete combustion 
by the electrical spark nearly two measures of-oxygene, and 
they formed nearly one measure of carbonic acid. 
' Sulphur heated strongly, and repeatedly sublimed in a 
portion of it freed from oxyger.e by phosphorus, produced 
a considerable enlargement of its volume, sulphuretted 
hydrogene was formed, and charcoal precipitated; and it 
was found that the volume of the sulphuretted hydrogene 
produced, when it was absorbed by solution of potassa, was 
exactly double that of the fire-damp decomposed. 
It did not act upon chlorine in the cold; but, when an 
electric spark was passed through a mixture of one part of it 
with two of chlorine, there was an explosion, with a dimi¬ 
nution to less than one quarter, and much charcoal was 
deposited. 
The analysis of . other specimens of gas afforded similar 
results; but they contained various quantities of carbonic 
acid gas and azote. 
Different specimens of these gases were tried by the test of 
exposure to chlorine both in darkness and light: they ex¬ 
hibited no marks of the presence of olefiant gas or hydro¬ 
gene ; and the residuum produced by detonation with 
chlorine showed them to be free from carbonic oxide. 
It is evident, then, that the fire-damp is the same substance 
as the inflammable gas of marshes, the exact chemical nature 
of which was first demonstrated by Mr. Dalton; and it con¬ 
sists, according to Sir H. Davy’s view of definite proportionsi 
of 4 proportions of hydrogene in weight 4, and 1 proportion 
of charcoal in weight 11.5. 
“I made,”says he, “several experiments on the combusti¬ 
bility and explosive nature of the fire-damp. When 1 part of 
fire-damp was mixed with 1 of air, they burnt by the approach 
of a lighted taper, but did not explode; 2 of air and 3 of 
air to 1 of gas produced similar results. When 4 of air and 
1 of gas were exposed to a lighted candle, the mixture being 
in the quantity of 6 or 7 cubical inches in a narrow necked 
bottle, a flame descended through the mixture, but there was 
no noise: 1 part of gas inflamed with 6 parts of air in a 
similar bottle, produced a slight whistling sound : 1 part of 
gas with 8 parts of air, rather a louder sound: 1 part with 
10, 11, 12, 13, and 14 parts, still inflamed, but the violence 
of combustion diminished. In 1 part of gas and 15 parts of 
air, the candle burnt without explosion with a greatly en¬ 
larged flame : and the effect of enlarging the flame, but in a 
gradually diminishing ratio, was produced as far as 30 parts 
of air to 1 of gas. 
“ The mixture which seemed to possess the greatest explo¬ 
sive power, was that of 7 or 8 parts of air to 1 of gas; but 
the 
