October 9th.
7 killed, 1 injured.
Fig. 25.
Crane Boiler, 5ft. 6in. high, and 2ft. 6in. diameter, with internal conical fire-box, with two cross tubes and a chimney at the top, ¼ inch plates, 75 lbs.
The outer shell of the boiler was rent into many pieces, leaving the central conical fireplace intact. The nature of the rents showed that the plate round the manhole, which was unstrengthened by a ring, had first given way, and all the other fractures had led away from that point. This is confirmed by the fact, that the manlid was thrown a good distance, with force enough to make its way through the timber walls of a cabin. The front plate divided into many pieces, and scattered right and left, while the back plate was thrown through a cabin in the opposite direction to the manhole.
The central flue showed a slight indication of overheating, but the construction was such that the upper portion passed through the steam space, and was always exposed to the action of the fire, without the protection of the contact of water. The manhole without a ring on its edge to strengthen the plate, and held in by two clamps, which caused additional strain when carelessly screwed up, was by far the weakest place. The engine was standing after a short time of working, and as the safety valve was very defective, and could be screwed down until tight, against almost any pressure, it is most probable that the pressure mounted much higher than usual, when the weakest part gave way, and led to the sudden tearing up and scattering of the whole fabric.
Faulty construction of both boiler and fittings, rendered it unable to bear that accumulated pressure, which the safety valve ought to have made impossible.
No.58. Durham.
October 13th.