THE ROYAL ARTILLERY INSTITUTION. 
33 
On these grounds I think the hypothesis that the powder was 
exploded by the elevation of temperature in the magazine must be 
rejected. 
In other words, I feel satisfied that the magazines fulfilled the 
requirement of keeping down the temperature by means of the 
vapour given forth by the alum. 
To what, then, are these two explosions attributable ? The 
answer is, I think, simple. They were due to the actual burning 
away of the iron at one point, the consequent penetration of the 
flame to the interior, and the explosion of the powder reached by 
the flame. There is direct evidence as to the burning away of the 
iron, because the door of No. 2 was found, as stated, to be so 
burnt through; and this was merely an enlargement of the effect 
which was noticed in No. 1 after six hours—a hole having been 
burnt through the outer case of that magazine. In both instances 
it appears that this effect was due to the direct impingement of 
the flame, directed by the blast-holes, upon the iron; for in both 
cases the hole was burnt on that side of the magazine which was 
most exposed to the action of the wind. 
In short, what happened was no doubt this :—The magazines 
amply fulfilled the object for which they had been constructed 
until the iron was actually burnt through , when explosions followed 
from the direct contact of the flame with the powder. It will 
perhaps be urged that the remedy for this is simple—viz., to make 
the iron thicker or stronger. To this suggestion I would reply by 
anticipation, 
1st. That no such increase of strength or thickness is necessary, 
since the resisting power is now considerably in excess of what is 
really required. 
2nd. That such an increase of thickness would be disadvan¬ 
tageous, in so far as it would increase the cost of the magazines, 
and so (in the absence of statutory provisions compelling dealers 
to provide them) would tend to reduce the number of purchasers. 
Moreover, if any purchaser desires an extra-resisting magazine, 
he can of course obtain one of the strength of No. 4. But for 
ordinary purposes, a magazine of the type of Nos. 1, 2, and 3 
would be entirely satisfactory, and may be regarded as thoroughly 
fire-proof. 
It is to be hoped that it will be found practicable to supply 
these magazines at a rate which will place them within the reach of 
retail dealers generally. Messrs. Milner inform me that they 
have no doubt of being able to supply them (to hold 100 lbs.) for 
10 guineas; and considering the great increase of public safety 
which would result from their general employment by retail 
dealers, it is a question whether their use for all cases in which 
sufficient isolation from dwelling-houses, stores, &c., and from the 
resulting fire cannot be secured, might not fairly be made com¬ 
pulsory. 
But in the absence of any provision to this effect, it is desirable 
that every encouragement should be given to dealers to adopt this 
5 
Explosion clue 
to burning 
away of iron 
and penetration 
of flame. 
Ground for not 
requiring any 
increase or 
alteration in the 
thickness of the 
iron. 
Desirability of 
securing gene¬ 
ral adoption of 
fire-proof 
magazines of 
this or other 
approved 
construction, 
for use in houses 
and crowded 
localities. 
