The explosion happened when in revolving, the manlid was downwards, and the lid was driven nearly through the floor, and the shell was rent from opposite corners of the manhole, and blown through the roof. The large manhole cut away nearly all the strength on one side, and the fastenings of the lid were not contrived to compensate at all for the loss of strength. The constant strain when revolving, also tended to weaken it. These two causes together were sufficient to account for the explosion, at the usual working pressure of 12 lbs., although it is possible that it might have been increased to 35 lbs., as that was the pressure in the boiler supplying the steam, although the pressure was regulated by a check valve. This explosion (and also No. 41 in this year) clearly show that a mere vessel of steam not exposed to the fire, or any chance of overheating of the plates, can burst and cause very great destruction, although there could be no sudden _increase of pressure_ which is so often supposed necessary to account for the havoc caused by explosions. _No. 64. Manchester. November 26th. none injured._ This Boiler was 28ft. long, 7ft. diameter, made of 7/16 inch plates, and worked at 50 lbs. pressure, with two internal fireplaces united into one tube beyond. The sides of the oval chamber forming the junction of furnaces and tube, crushed inwards, being of such a weak shape as to be unable to resist the ordinary working pressure. _No. 65. Hull. (Fig. 31.) December 1st. 3 killed, 2 injured._ [Illustration: _Fig. 31._] Agricultural, 7ft. 6in. long, and 3ft. 8in. diameter, 1/4 inch plates, 35 lbs., fire-box 2ft. long, and 2ft. 10in. broad. Two 11-1/2-inch tubes led to an internal chamber at the other end of the boiler, and three 8-1/4-inch tubes led back again to an external smoke box and chimney fixed over the fire door. The bottom of the right hand side lower tube was forced upwards, and rent along to within 12 inches of the fire-box. The tubes were so corroded from leakage of patches, that they were unable to bear the slight increase of pressure during a short stoppage. _No. 66. Glasgow. December 4th. 2 killed, 6 injured._ Two Tube Cornish, 22ft. long, and 7ft. 6in. diameter, tubes 3ft. diameter, and strengthened with rings in the approved manner. The second from the back of the seven rings, was ruptured at the bottom and torn off by a rent through the line of rivets on each side, and the boiler was thrown from its seat, and turned completely over, so as to lie in a contrary direction to what it was before. Extensive corrosion, from leaking of the seams beneath the brickwork, where hidden from view, was the cause of explosion. _No. 67. Willenhall. December 7th. none injured._ Plain Cylinder, with hemispherical ends, 9ft. long, 3ft. 3in. diameter, 20 lbs.