SAFE GUNPOWDER MAGAZINE.

417

a wood fire was kept up at the bottom for several daystill the coating at last was perfectly dry to a considerabledepth. A mixture of oil and lime was plentifully applied,so as to fill up every little crack and saturate the plasterand wall.

The superstructure for the door and roof above thesurface of the ground was made as slight as possible, aswas also the roof. The object I had in view in thisconstruction was, to confine the effects of an explosionto a vertical rise in the air, much more so even than in thespringing of a mine; and, moreover, a part of my plan wasto give the pit, if the locality require it, an inclinationfrom the perpendicular of several degrees, so as to directthe possible explosion towards the point where the leastdamage would accrue. There are many ways of renderingsuch a magazine perfectly dry and water tight, all tooobvious for me to describe. As a means of abstractingfrom the confined air, a great portion of the water held insolution, I constructed several copper cylinders drilled fullof holes, which being filled with lumps of fresh and wellcalcined lime, and suspended from several points of the roofat various altitudes, absorbed the moisture if any existed.

However, well made gunpowder is not nearly so de-liquescent as is generally supposed; it only becomes sowhen made with impure nitre, and too large a portion ofcharcoal.

A magazine of only the above dimensions will containconveniently above one thousand barrels of gunpowder,and any number of such constructions may be clustered intoone common enclosure in any eligible situation. I amdecidedly in favour of lightning conductors for thepreservation of every kind of buildings and of ships,from the injurious effects of electric discharges. I have

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