| Cornish, Lancashire, or other boilers with internal flues | 84 |
| Plain Cylindrical boilers or others without internal flues | 54 |
| Marine boilers | 12 |
| Agricultural boilers | 11 |
| Locomotive boilers | 10 |
| Furnace-upright boilers | 8 |
| Crane boilers | 6 |
| Rag steamers, &c. | 6 |
| Balloon and Elephant boilers | 5 |
| Domestic boilers, &c. | 16 |
| Not sufficiently described | 7 |
| Total | 219 |
The causes of these 219 explosions may also be classed as follows:—
| Worn out, corroded, or burnt plates | 89 |
| Undue pressure, overloaded valves, intentional or from carelessness | 25 |
| Bad construction, defective fittings or stays, or want of repair | 69 |
| Shortness of water, formation of scale or mud, or external flues set too high | 28 |
| Extraneous or uncertain causes | 8 |
| Total | 219 |
Sketches are given of the most instructive examples of boiler explosions during the last four years, which are sufficient to explain themselves, with a brief reference to their special features.
Fig. 1.
Fig. 2.