148 Mr Stevenson's Account of the Explosion of a 
about 4 feet in height ; and the bottom, forming a semicircle, 
rose into the body of the boiler. Its cross-section was of a cres- 
cent form, as will be seen by referring to Plate I. Fig. 17., a 
construction adopted with a view to the more ready and benefi- 
cial circulation of the heat of the furnace. The whole weight of 
the boiler is said to have been about 9 tons ; of which the top 
and sides were estimated to weigh about 7 tons. This large 
proportion of 7 tons weight was torn from the bottom by the ex- 
pansive force, and thrown up with such amazing impetus, that 
it dashed aside its arched covering of brick-work, penetrated the 
roof of the boiler-house, and, according to the estimate of those 
who witnessed the scene, rose into the atmosphere to the height 
of not less than 70 feet before it began to descend. On the south, 
the boiler-house was flanked by other buildings ; while it was 
free on the north. Owing to this circumstance, the projected mass 
naturally received an inclination to the northward, and, describing 
an arch in its passage through the air, it alighted on the roof of 
the great mash-house of the distillery, situate at the distance of 
150 feet from the boiler-house, and in its fall carried every thing 
before it. Even the floor of the mash-house was broken up, 
and one side of a large circular mashing-vat of cast-iron was 
crushed in pieces. 
To illustrate the expansive force still farther, we may ob- 
serve, that the boiler was constructed of malleable iron plates, 
three-eighths of an inch in thickness, and only 8 inches in 
breadth. With a view to bind and strengthen the cross-section 
of the boiler, it was set upon thirty-six bars of cast-iron, measure 
ing d inches in depth, by inches in thickness, forming so many 
ties across the semicircular bottom. Notwithstanding these pre- 
cautions, we see, that the top and sides of this ponderous vessel 
were wrested from its bottom ; and, though weighing about 7 
tons, as before noticed, were projected into the air about 70 
feet, and fell at the distance of 150 feet. It also deserves 
our particular notice, that the bottom, though lifted with 
the top and sides at least to the height of 14 or 15 feet, was 
found deposited among the rubbish merely on the outside of the 
boiler-house ; it was bent, however, from its regular semicircular 
