262 
MINUTES OF PROCEEDINGS OF 
its commencement—appear to have gradually succeeded in very im¬ 
portantly reducing the annual number of boiler explosions by introducing 
among its members a system of periodical independent inspection the 
efficiency of which is clearly demonstrated by the circumstance that no 
case of explosion has yet occurred with boilers under the regular inspec¬ 
tion of the Association, while between 600 and 800 boilers are examined 
monthly. The periodical reports prepared by the talented chief engineer 
of the Association, Mr. Lavington Fletcher, are full of interesting and 
valuable information, and throw great light upon the chief causes of 
boiler explosions and the means by which they may be guarded against. 
The Association will not allow that the term “ accidental,” or “ mys¬ 
terious,” is applicable to steam-boiler explosions. Mysterious they 
certainly are not, as they are generally quite traceable to causes which 
may be obviated—such as inferior material, or defective construction, 
or local injuries, gradually developing and increasing, which would 
certainly be discovered before they attained dangerous dimensions by a 
proper inspection; it may therefore not be too harsh to maintain that 
boiler explosions are not accidental, as their prevention lies in the 
power of the steam users—though it is true the same view must equally 
apply to other classes of so-called accidental explosions which are 
referred to in this discourse. 
The following statements, furnished to the speaker by the Steam 
Users J Association, afford some idea of the number and nature of boiler 
explosions which have occurred in the last few years. The number of 
explosions recorded annually by the Association, from 1865 to 1874 
inclusive, ranges from forty-eight to seventy-two; the average present 
annual number is fifty. The largest number of deaths recorded is 
eighty-seven, and the smallest thirty-two, the present average number 
being seventy-five. About double that number of persons are seriously 
injured annually. With respect to the causes of boiler explosions, 40 
per cent, were due (from January, 1861, to June, 1870) to malconstruc- 
tion of the boilers, 29 per cent, to “ defective condition” of the boilers, 
15 per cent, to the failure of seams of rivets at the bottom of externally 
fired boilers, 10 per cent, to overheating from shortness of water, and 
less than 3 per cent, to accumulation of incrustations.* 
An examination into the particular nature of the services performed 
by boilers which have exploded shows that a considerable number of 
explosions have occurred at iron works, and a very large proportion at 
collieries, where plain cylindrical externally-fired boilers are much used. 
Many of the explosions of these particular boilers arise from weak places 
which remain for a time concealed in the overlaps of the seams of rivets, 
defying detection, but gradually extending from one rivet-hole to 
another till some sudden strain causes them to extend throughout the 
entire seam, the boiler splitting in two. The particular description of 
boiler which gave rise to the largest number of fatal accidents during 
the year taken as illustration (1873) was the single-flued or Cornish 
boiler; and it was stated by Mr. Fletcher that all these explosions 
* These data are in part extracted from a table submitted bj Mr. Fletcher to the Select Committee 
on Boiler Explosions, in June, 1870. (Vide p. 118 of the Committee’s Report.) 
