THE ROYAL ARTILLERY INSTITUTION. 
259 
ON THE 
“TIME OF BURNING” OF FUZES UNDER DIFFERENT 
ATMOSPHERIC PRESSURES. 
Extracted from Comptes Rendus hebdomadaires des Seances de l’Academie des Sciences. 
Vol. LY. No. 21. 
Translated from tlie Trench of M. Dufouii (of Lausanne), 
By Major EITZHUGH, R.A. 
Up to the present time there are but few "data” available for an enquiry 
into the influence exerted by atmospheric pressure on the rate of combustion 
of fuzes. 
These "data” appear also to be sometimes contradictory; thus in 1841 
M. Triga noted an increased rapidity of combustion in candles placed in an 
enclosure, where the air was under a pressure of three atmospheres, whereas 
soon afterwards Mr Erankland, during an ascent of Mont Blanc, detected 
no sensible difference between the combustion of candles burnt at Chamou- 
nix and the combustion of those burnt on the top of the mountain. 
In 1855, Mr Mitchell, Quarter-master in the English army, communicated 
to the Royal Society the result of experiments made at various elevations in 
the Himalayas with military fuzes. His results show that the time of burn¬ 
ing increases as the pressure diminishes. 
The combustion therefore appears to be less active under a lower pressure. 
Mr Erankland last year repeated the experiments of Mr Mitchell and 
confirmed his results. Mr Erankland experimented on 6-in. fuzes, made at 
the Arsenal, Woolwich; these fuzes were burnt in a close vessel in air artificially 
rarefied. 
In the experiments of Mr Erankland the pressure unavoidably varied a 
little during the burning of the same fuze, and in spite of the ingenious 
contrivances used by this scientific man, it is to be feared that the combustion 
was influenced by the smallness of the space in which it took place. 
In the month of July last, I tested the time of burning of fuzes under 
circumstances different from those under which the scientific English physi¬ 
cian made his experiments; I experimented in the open air, seeking pressures 
gradually lower and lower at different altitudes in the Alps. 
It is very difficult to determine accurately the duration of combustion of a 
fuze if the observer trusts to being able to note on any sort of time-piece the 
instant at which the fuze takes fire, and goes out. 
Errors in noting these instants, which errors may vary in different cases, are 
very likely to vitiate the conclusions drawn from the experiments. 
