Chapter III: Part 3

In order to enable boiler minders to make proper periodical examinations, it is necessary that care should be taken to arrange both the boilers and the flues with that view; and this can be done without materially injuring the efficiency of the boiler. Ordinary plain cylindrical boilers can be entered easily, as in Fig. 42; and although the small spaces between the tubes and the shells of Cornish and Lancashire Boilers, as shown in Fig. 43, render the complete examination troublesome, there is no difficulty in seeing those parts most likely to need examination, such as the crowns of the tubes and the end plates and angle iron. It is in the external flues that greater accommodation is needed, as in many cases these are so narrow that the boiler is quite inaccessible without pulling down the brickwork, as in Figs. 44 and 45. The loss of heating effect caused by the use of wider flues is so little, that it is far outweighed by the greater security obtained from the more efficient examination that is thereby rendered practicable. The flues of the plain cylindrical boiler are easily made wide enough for a man to pass through them. The flues of Cornish and Lancashire boilers should be made as shown in Figs. 46 and 47, so that a man can enter them without such inconvenience as in Fig. 48. One point of danger being the use of wide mid-feather walls, on which corrosion is apt to take place, these should be narrowed and the weight of the boiler supported on side brackets; the top of the mid-feather and side walls can then be constructed with sight holes as at A A in Figs. 49 and 50, so as to give the means of examining the plates near each seam by simply removing loose bricks.

The explosions of fourteen Domestic or Heating-Apparatus Boilers are included in the list of explosions, Table III; and some notice is required to be taken of these, because they have led to the loss of the lives of those who could not be expected to know their construction or how to guard against accident; and as these boilers are seldom seen or examined after they are once set, they should be the more carefully constructed. In one or two cases these boilers were of a rectangular shape, as in Fig. 51, No. 41, 1868, ill adapted to bear internal pressure, and yet placed in connection with cisterns in the roofs of lofty houses, so as to expose them to a hydrostatic pressure almost up to their bursting strength without any addition of steam pressure. The most usual cause of explosion is the lighting of the fire during frosty weather in a house that has been left vacant, so that steam pressure accumulates in the boiler whilst the exit is frozen up, as was the case in Fig. 52, No. 6, 1870. The cast-iron boilers commonly used, Fig. 53, end of 1869, are capable of bearing but little pressure; and the wrought iron boilers, as in Fig. 54, No. 7, 1870, are found often so badly welded as to be but little stronger; but even if they were as strong as they could be made, the stoppage of the pipes by ice would lead to explosion. Steam pressure may be guarded against by a safety valve; but as this may become set fast in a little time, it would be far better to avoid all chance of steam accumulation by such an arrangement as that shown in Fig. 55, where the circulating boiler is placed within an open-topped boiler behind the kitchen fire, and only receives its heat through the hot water surrounding it, and therefore cannot itself become sufficiently hot to generate steam.

* * * * *

A few remarks may be useful as to those faults arising in working which fall under the department of the boiler minders. Not a few of the explosions during the last four years have occurred from acts of simple carelessness, such as where a blow-off pipe was left open, so that the boiler was nearly emptied of water while at work; or in another case where two boilers were fed at the same time through a common pipe without a back valve, and the water from one "kicked" over into the other. Undue pressure has been allowed to accumulate by safety valves being tied down, as in the agricultural boiler, Fig. 56, No. 16, 1867; or by an extra weight being put upon the safety valve, as in an instance where three bricks were fastened to the lever and the fires were lighted earlier than usual, under the idea that an accumulation of steam could be raised during the night to make a good start in the morning. Another explosion was caused by working a boiler at more than three times its proper pressure to meet a temporary emergency. In not a few cases of explosion there was no pressure gauge on the boiler, or the gauge was out of repair in consequence of being placed on the steam pipe, so that it vibrated with every stroke of the engine; as in the examples shown in Figs. 24 and 16, No. 35, 1868, No. 32, 1870, pages 70 and 74.

Corrosion has been the direct cause of many of the explosions. In one or two cases the corrosion was known to exist, but the renewal of the boiler was too long delayed, as in Fig. 57, No. 8, 1869, in others it took both owners and minders by surprise, as in Fig. 1, No. 12, 1870, page 63. It is said that to produce rapid rusting of iron there must be present oxygen, water, and carbonic acid; and as all these are present in a boiler flue when there are leaks, it is not surprising that so many cases occur of explosions from corrosion.

* * * * *

Much mischief is often done by the injudicious use of compositions in the boiler that are designed to prevent incrustation, especially where there is no blow-off cock or where its use is neglected. A hard deposit on the boiler plates is, in the writer's opinion, not so injurious as the soft and muddy deposit produced by the use of such compositions. A hard scale is equivalent to thickening the plate; and although this is sufficiently mischievous, the injury to the plates is much more rapid when a thicker but spongy deposit entirely prevents contact of the water and impedes the transmission of the heat. An attempt to illustrate this is given in Fig. 58, which is an enlarged view of a portion of such a boiler as is shown in Fig. 37. The money spent in boiler compositions would be better applied in securing a supply of proper water, or in filtering and purifying the water before it enters the boiler.

The writer has had to mention only faults in boilers; but it is not to be inferred that all boilers are working in actual danger. A very small percentage perhaps are so; but without periodical examination no one can feel sure of the condition of any boiler. It is not likely that explosions in future will be from exactly the same causes as those now described, because the known faults will be avoided. For instance no new Balloon, Wagon, or Butterley boilers are now made; and the peculiar faults and the weakness of the tubes in Cornish and others of the better classes of boilers are now so well known as to be generally avoided; and as information spreads, many evils will become things of the past.

As periodical examination has been so strongly advocated, it might seem natural to desire that it should be enforced by government authority; but this is by no means recommended. A select parliamentary committee has been recently investigating the subject, with a view to ascertain whether that would be desirable, but has adjourned for the session without coming to any decision on this point. Even if a perfect system of government inspection could be contrived and perfectly administered, it would have the effect of taking the responsibility from the owners, who are the natural guardians of the safety of their boilers. Although the loss of 70 lives per annum by boiler explosions is sufficiently deplorable, the deaths by railway accidents are more than three times that number; yet very little inspection of railways is held to be necessary, and that inspection takes place chiefly before the commencement of working or after accidents. A coercive system may introduce more evils than it cures, especially as at present so much difference of opinion exists respecting the causes of boiler explosions. In the opinion of the writer, far more real good arises from the calm discussion of the facts and from the spread of correct information by such societies as this Institution, than from enforcing by law any action which is not perhaps believed by the majority of steam users to be at all necessary or useful. It has been at times suggested to increase the power and responsibility of coroners in holding inquests upon those killed by boiler explosions, by requiring them to obtain scientific evidence and to insist that the causes of the explosions shall be added to the verdicts of juries. But it is believed that this would only encumber an important institution, because a jury who might well decide whether a person had been killed by any criminal carelessness would not be a suitable tribunal to decide between possibly conflicting scientific evidence; and also, as an inquest may result in a verdict of manslaughter, the eliciting of information on such an occasion is checked by the natural fear of inadvertently involving some one in so serious a charge. The public at large, and steam users generally, would gain more information and guidance from the scientific evidence itself than from the verdict of a coroner's jury; and it is believed much good has resulted in preventing locomotive boiler explosions by publishing the reports of the government inspecting engineers, who have gained their knowledge of the facts in conversation with all those concerned, and have added recommendations which have been promptly acted upon.

The writer's object has been that the boilers found most convenient and best suited for the different purposes for which they are used should be made to work with safety, rather than that reliance should be placed upon the qualities of any particular kind of boiler or fittings. No form of boiler at present admits of absolute reliance upon its freedom from risk.

The following general conclusions appear to arise from the consideration of the records of boiler explosions.

1. That the force accumulated in an ordinary boiler is enough to account for the violence of an explosion.

2. That no form of boiler, however well constructed and fitted, is free from the liability to explosion, if allowed to get out of order; and that boilers which bear the hydraulic test may still be dangerous.

3. That the condition of a boiler can be satisfactorily ascertained only by periodical examinations, and that no boiler should work without being thoroughly examined at short intervals.

4. That the cost of periodical examination is so little as to be far outweighed by the greater security obtained; and that the settings of all boilers should be constructed with a view to facilitate examination.

5. That the surest way to make systematic examination general is to spread as widely as possible correct information as to the facts and ascertained causes of boiler explosions, and to inform boiler owners and minders what dangers to guard against; and that this is preferable, and more likely to lessen explosions than enforcing any system of inspection by legal enactment.

TABLE I.

_Summary of Records of Steam Boiler Explosions_
_up to 30th June, 1870,_
_showing Description of Exploded Boilers._

+------------------++-----------------------++-----------------------+
| Description of || Explosions up to June || Explosions in the 4 |
| Boiler. || 1866. || years from June 1866 |
| || || to June 1870. |
+ |+--------+--------+-----++--------+--------+-----+
| ||English.|Foreign.|Total||English.|Foreign.|Total|
+==================++========+========+=====++========+========+=====+
|Marine || 57 | 203 | 320 || 12 | 64 | 76 |
+------------------++--------+--------+-----++--------+--------+-----+
|Cornish, || 140 | 1 | 141 || 84 | 3 | 87 |
|Lancashire, or || | | || | | |
|others with || | | || | | |
|internal flues || | | || | | |
+------------------++--------+--------+-----++--------+--------+-----+
|Locomotive || 91 | 29 | 120 || 10 | 68 | 78 |
+------------------++--------+--------+-----++--------+--------+-----+
|Plain Cylindrical || 114 | 2 | 116 || 54 | 3 | 57 |
|externally fired || | | || | | |
+------------------++--------+--------+-----++--------+--------+-----+
|Balloon, || | | || | | |
|Haystack, Wagon, || 62 | 2 | 64 || 5 | 2 | 7 |
|Butterley, || | | || | | |
|British-Tube || | | || | | |
|Elephant, or || | | || | | |
|Trevithick || | | || | | |
+------------------++--------+--------+-----++--------+--------+-----+
|Portable, || | | || | | |
|Agricultural, || 28 | 1 | 29 || 17 | 17 | 34 |
|Upright, Crane, || | | || | | |
|or very small || | | || | | |
+------------------++--------+--------+-----++--------+--------+-----+
|Heating, Kitchen, || 14 | .. | 14 || 22 | 14 | 36 |
|Domestic, Rag || | | || | | |
|Steamers, &c. || | | || | | |
+------------------++--------+--------+-----++--------+--------+-----+
|Furnace-upright || 10 | .. | 10 || 8 | .. | 8 |
+------------------++--------+--------+-----++--------+--------+-----+
|Not sufficiently || 203 | 29 | 232 || 7 | 175 | 182 |
|described to be || | | || | | |
|classified || | | || | | |
+==================++========+========+=====++========+========+=====+
|Totals || 719 | 327 |1046 || 219 | 346 | 565 |
+------------------++--------+--------+-----++--------+--------+-----+

TABLE I (continued)

+------------------++--------------------------+
| Description of || Total Explosions |
| Boiler. || up to June, 1870. |
| |+--------+--------+--------+
| ||English.|Foreign.| Total. |
+==================++========+========+========+
|Marine || 69 | 327 | 396 |
+------------------++--------+--------+--------|
|Cornish, || 224 | 4 | 228 |
|Lancashire, or || | | |
|others with || | | |
|internal flues || | | |
+------------------++--------+--------+--------+
|Locomotive || 101 | 97 | 198 |
+------------------++--------+--------+--------+
|Plain Cylindrical || 168 | 5 | 173 |
|externally fired || | | |
+------------------++--------+--------+--------|
|Balloon, || | | |
|Haystack, Wagon, || 67 | 4 | 71 |
|Butterley, || | | |
|British-Tube || | | |
|Elephant, or || | | |
|Trevithick || | | |
+------------------++--------+--------+--------+
|Portable, || | | |
|Agricultural, || 45 | 18 | 63 |
|Upright, Crane, || | | |
|or very small || | | |
+------------------++--------+--------+--------+
|Heating, Kitchen, || 36 | 14 | 50 |
|Domestic, Rag || | | |
|Steamers, &c. || | | |
+------------------++--------+--------+--------+
|Furnace-upright || 18 | .. | 18 |
+------------------++--------+--------+--------+
|Not sufficiently || 210 | 204 | 414 |
|described to be || | | |
|classified || | | |
+==================++========+========+========+
|Totals || 938 | 673 | 1611 |
+------------------++--------+--------+--------+

TABLE II.

_Summary of Records of Steam Boiler Explosions_
_up to 30th June, 1870,_
_showing Causes of Explosions._

+-----------------++------------------------++------------------------+
|Cause of || Explosions up to June || Explosions in the 4 |
|explosion. || 1866. ||years from June 1866 to |
| || || June 1870. |
| |+--------+--------+------++--------+--------+------+
| ||English.|Foreign.|Total.||English.|Foreign.|Total.|
+=================++========+========+======++========+========+======+
|Worn out, || 92 | 53 | 145 || 89 | 5 | 94 |
|corroded, or || | | || | | |
|burnt plates || | | || | | |
+-----------------++--------+--------+------++--------+--------+------+
|Undue pressure, || 132 | 5 | 137 || 25 | 6 | 31 |
|overloaded || | | || | | |
|valves, || | | || | | |
|intentional or || | | || | | |
|from carelessness|| | | || | | |
+-----------------++--------+--------+------++--------+--------+------+
|Bad || 136 | 108 | 244 || 69 | 8 | 77 |
|construction, || | | || | | |
|weak tubes, || | | || | | |
|defective || | | || | | |
|fittings or || | | || | | |
|stays, or want || | | || | | |
|of repair || | | || | | |
+-----------------++--------+--------+------++--------+--------+------+
|Shortness of || 106 | 8 | 114 || 28 | 2 | 30 |
|water, formation || | | || | | |
|of scale or mud, || | | || | | |
|or external || | | || | | |
|flues set too || | | || | | |
|high || | | || | | |
+-----------------++--------+--------+------++--------+--------+------+
|Extraneous || 6 | 3 | 9 || 2 | .. | 2 |
|causes, || | | || | | |
|lightning, fire, || | | || | | |
|gas, &c. || | | || | | |
|-----------------++--------+--------+------++--------+--------+------+
|Too uncertain to || 247 | 150 | 397 || 6 | 325 | 331 |
|be classified || | | || | | |
|=================++========+========+======++========+========+======+
|Totals || 719 | 327 | 1046 || 219 | 346 | 565 |
+-----------------++--------+--------+------++--------+--------+------+

Table II (continued)

+-----------------++------------------------+
|Cause of || Total Explosions up to |
|explosion. || June 1870. |
| || |
| |+--------+--------+------+
| ||English.|Foreign.|Total |
+=================++========+========+======+
|Worn out, || 181 | 58 | 239 |
|corroded, or || | | |
|burnt plates || | | |
+-----------------++--------+--------+------+
|Undue pressure, || 157 | 11 | 168 |
|overloaded || | | |
|valves, || | | |
|intentional or || | | |
|from carelessness|| | | |
+-----------------++--------+--------+------+
|Bad || 205 | 116 | 321 |
|construction, || | | |
|weak tubes, || | | |
|defective || | | |
|fittings or || | | |
|stays, or want || | | |
|of repair || | | |
+-----------------++--------+--------+------+
|Shortness of || 134 | 10 | 144 |
|water, formation || | | |
|of scale or mud, || | | |
|or external || | | |
|flues set too || | | |
|high || | | |
+-----------------++--------+--------+------+
|Extraneous || 8 | 3 | 11 |
|causes, || | | |
|lightning, fire, || | | |
|gas, &c. || | | |
|-----------------++--------+--------+------+
|Too uncertain to || 253 | 475 | 728 |
|be classified || | | |
|=================++========+========+======+
|Totals || 938 | 673 | 1611 |
+-----------------++--------+--------+------+

TABLE III.

_Analysis of Steam Boiler Explosions in the United Kingdom_
_during the Four years ending 30th June, 1870,_
_showing the Causes of Explosion of Boilers of different descriptions._

A = Faults in construction or repair.
B = Faults which should be detected by periodical examination.
C = Faults which should be prevented by careful attendants.
D = Causes extraneous or uncertain.
E = number of Explosions.
K = number of persons Killed.
I = number of persons injured.

CORNISH, LANCASHIRE, _or other Boilers with internal flues_.

_E_ _K_ _I_
{Weak Tubes 26 17 41
{Weak combustion chambers 5 8 7
A {Weak ends 3 10 10
{Weak dome 1 0 0
{Weak manhole 1 1 1
{Bad repair 3 5 2 _E_ _K_ _I_
------------ 39 41 61
B {External Corrosion 18 42 101
{Internal Corrosion 6 4 5
------------ 24 46 106
{Shortness of Water 14 11 23
C {Scale of mud 3 1 0
{Undue Pressure 4 14 4
------------ 21 26 27 _E_ _K_ _I_
------------ 84 113 194

PLAIN CYLINDRICAL, _or other Boilers without internal flues_.

_E_ _K_ _I_
{Weak flat ends 8 9 12
{Weak manhole 1 0 2
{Frequent repair producing }
A { seam rip in boilers with } 15 18 28
{ plates arranged lengthways}
{Do. with plates arranged in }
{ rings } 8 11 25
------------ 32 38 67
B {External Corrosion 11 5 19
{Internal Corrosion 5 5 6
------------ 16 10 25
{Shortness of Water 2 1 0
C {Scale 1 1 0
{Undue pressure 3 4 3
------------ 6 6 3
------------ 54 54 95
------------

MARINE BOILERS.

_E_ _K_ _I_
{Weak flues 3 6 3
A {Weak ends 2 6 5
{Bad material 1 3 _E_ _K_ _I_
------------ 6 15 9
B {External Corrosion 2 10 3
{Internal Corrosion 3 1 4
------------ 5 11 7
C Shortness of water 1 11 7
------------ 1 11 7
------------ 12 37 23

LOCOMOTIVE BOILERS.

A Boiler used as frame for engine 2 1 2
------------ 2 1 2
B {External Corrosion 2 1 4
{Internal Corrosion 2 0 3
------------ 4 1 7
{Broken connecting-rod }
D { pierced boiler } 1 2 1
{Dome caught by railway bridge } 1 1 0
{Uncertain causes } 2 0 4
------------ 4 3 5
----------- 10 5 14

AGRICULTURAL BOILERS.

A Weak manhole 1 1 4
------------ 1 1 4
B {External Corrosion 2 3 3
{Internal Corrosion 1 1 7
------------ 3 4 10
C {Shortness of water 1 0 0
{Undue pressure 6 15 15
------------ 7 15 15
----------- 11 20 29

FURNACE UPRIGHT BOILERS.

{Too much flame on one part 1 2 0
A {Frequent repair producing }
{ seam rip } 1 13 2
------------ 2 15 2
B {External Corrosion 2 13 11
{Internal Corrosion 2 15 6
------------ 4 28 17
C Shortness of Water 2 3 8
------------ 2 3 8
----------- 8 46 27

ELEPHANT BOILERS.

A Weak ends or want of stays 1 2 2
------------ 1 2 2
B External Corrosion 1 0 4
------------ 1 0 4
----------- 2 2 6

CRANE BOILERS.

_E_ _K_ _I_
A Weak manhole 3 7 3 _E_ _K_ _I_
------------ 3 7 3
B External Corrosion 1 4 2
------------ 1 4 2
C Shortness of water 2 2 0
------------ 2 2 0
----------- 6 13 5

RAG STEAMERS, &C.

{Weak manhole 3 2 5
A {Bad material 1 1 5
{Want of stays 1 1 0
------------ 5 4 10
C Undue Pressure 1 2 6
------------ 1 2 6
----------- 6 6 16

FEED-WATER HEATERS.

D Uncertain causes 2 0 6
------------ 2 0 6
----------- 2 0 6

DOMESTIC BOILERS.

A Weak shape 3 4 7
------------ 3 4 7
B Corrosion 2 0 5
------------ 2 0 5
C Undue Pressure from }
freezing of Pipes } 9 7 9
------------ 9 7 9
----------- 14 11 21

BALLOON BOILERS.

B External Corrosion 2 1 2
------------ 2 1 2
C Undue Pressure 1 1 0
------------ 1 1 0
----------- 3 2 2

BOILERS OF UNCERTAIN DESCRIPTION.

A Weak manhole 1 0 0
------------ 1 0 0
{Steam entered through blow- }
{ off pipe from another boiler} 1 1 2
C { while cleaning }
{Steam pipes broken 2 4 3
{Shortness of Water 1 1 4
------------ 4 6 9
D Uncertain causes 2 0 3
------------ 2 0 3
----------- 7 6 12
----------
_E_ _K_ _I_
TOTALS 219 315 450

TABLE IV.

_Summary of causes of the Steam Boiler Explosions comprised in Table III._

+-----------------------------------+-----------+---------+---------+
| | E | K | I |
| | Number |Number of|Number of|
|Causes of Explosion. | of | persons | persons |
| |Explosions.| Killed. |Injured. |
+-----------------------------------+-----------+---------+---------+
|A Faults in construction or repair | 95 | 128 | 167 |
+-----------------------------------+-----------+---------+---------+
|B Faults which should be detected }| 62 | 105 | 185 |
| by periodical examination }| | | |
+-----------------------------------+-----------+---------+---------+
|C Faults which should be prevented}| 54 | 79 | 84 |
| by careful attendants }| | | |
+-----------------------------------+-----------+---------+---------+
|D Extraneous or uncertain causes | 8 | 3 | 14 |
+===================================+===========+=========+=========+
|Totals | 219 | 315 | 450 |
+-----------------------------------+-----------+---------+---------+

BRIEF ABSTRACTS
FROM REPORTS ON
STEAM BOILER EXPLOSIONS,
PRESENTED TO THE
MIDLAND STEAM BOILER INSPECTION & ASSURANCE Co.,
BY
EDWARD BINDON MARTEN,
CHIEF ENGINEER TO THE COMPANY.

_Description is shortened as much as possible, and facilitated by slight sketches, showing the position of the fragments or line of fracture, and the general construction of the Boilers._

REPUBLISHED BY THE PERMISSION OF THE COMPANY.

STOURBRIDGE: B. BROOMHALL, PRINTER, HIGH STREET.
1869.

BOILER EXPLOSIONS IN 1866.

_No. 1. Nottingham. January 1st. none injured._

Locomotive, 110 lbs., standing with steam up near a platform. All but the fire box was blown away, the main portion being thrown a distance of 400 yards. The first rent took place at a longitudinal seam of the barrel where grooving had gone on very rapidly, which was not discovered when examined and tested a short time before.

_No. 2. Walsall. (Fig. 1.) January 2nd. 2 injured._

Butterley, 26ft. 6in. long, and 9ft. diameter. The wagon-shaped top to the fire place was 8ft. 6in. long, and was attached to the bell-mouth of the internal tube, which then continued circular to the back of the boiler. The tube was 3ft. 6in. diameter. All the plates were about 7/16ths inch thick, and although the boiler was an old one, they were nowhere reduced in thickness by wear. The usual pressure of steam was 18 lbs., and a self-registering gauge showed that at the time of explosion it did not exceed 20 lbs.

The top of the fire grate on the right side rent longitudinally, and the upper part of the shell consisting of four rings of plates, and also the top of the fire place opened out and blew away to a considerable distance.

The front end also blew away. The bell-mouth of the tube was blown to the front, and the tube which remained in the back part of the shell collapsed upwards.

The cause of the explosion was most likely the intrinsic weakness of boilers of this shape, especially over the fire, where the top is only retained in its shape by numerous stays. The boiler had been very frequently repaired, at this the weakest place, and its strength had been thus so reduced as to make it unable to bear even a few pounds more than the ordinary working pressure.

The whistle was found to have been gagged by hemp, carefully inserted, so that there is ground for supposing there had been intentional unfair usage.

_No. 3. Blyth. (Fig. 2.) January 8th. 1 killed 1 injured._

Marine, 20ft. long, and 5ft. diameter, with internal fire place and return flue, 14 lbs. There were altogether three rents in the tube over the fire, as a small band was held in its place by a stay from the tube to the shell. The escaping contents scalded those near, but no damage was done to anything but the boiler.

The cause was stated to be shortness of water. There was no water gauge.

_No. 4. London. January 9th. 1 killed._

One tube Cornish, 28ft. long, 6ft. 6in. diameter, with one tube 3-6 diameter, 3/8 inch plates, 45 lbs.

The tube collapsed in an incline direction from weakness without strengthening rings.

The appearance after explosion was nearly the same as that shown in sketch given at No. 12 explosion.

_No. 5. Glasgow. (Fig. 3.) January 13th. 4 killed, 4 injured._

Two tube Cornish, 22ft. 3in. long, and 7ft. 7in. diameter, 3/8 inch plates, tubes 2ft. 7in. diameter, 40 lbs.

About 8ft of the back portion of the shell was torn off, leaving the tubes and ends intact.

The cause of the explosion was considered to be excessive pressure, but how accumulated did not transpire.

It is most natural to expect that there must have been corrosion under the bottom to cause the first rent.

_No. 6. Coatbridge. January 17th. 1 injured._

Cornish. No details have been obtained.

_No. 7. York. (Fig. 4.) January 18th. 1 killed, 2 injured._

Agricultural, 8ft. 2in. long, 3ft. 6in. diameter in the barrel, 5/16ths inch plates, internal fire box, 2ft. 4in. wide, 2ft. 4in. high, and 2ft. 10in. deep. From the back of this fire box, two 12-inch tubes passed to an internal chamber at the back of the barrel. From this again passed nine 3-3/4 inch tubes to an exterior smoke-box fixed over the fire door. The boiler was fitted with one spring safety valve, which was screwed down tight, but there was no pressure gauge. The front plate was intended to be bolted on so that the fire-box and tubes could be taken out for cleaning, but it had been rivetted, leaving no means of cleaning, and it was nearly full of scurf.

The crown plate of fire-box which was too flat and unstrengthened, rent at the front and along both top edges, and was driven into the fire. The boiler was thrown backwards and reared against a wall, resting on the front right hand corner.

The cause of the explosion was that the very dirty state, caused overheating where the water was not in proper contact with the plates, and the defective construction did not admit of proper cleaning. The mountings were insufficient for the proper protection of the boiler.

_No. 8. Durham. (Fig. 5.) January 29th. 1 killed, 3 injured._

Plain Cylinder Boiler with hemispherical ends, 30ft. long and 6ft. diameter, 3/8 inch plates, 30 lbs. It was the second from the engine in a bed of five, and had been at work three years, then remained idle for eight years, working again fourteen years. The boiler was mounted with two safety valves 3-7/8 and 4 inches diameter, a float and alarm whistle. The boiler had been more than once repaired over the fire with several new plates. One seam over the fire had been observed to leak about a week before the explosion, but not seriously, and had been caulked. The boiler had just been started after cleaning. Six months before explosion, the boiler had been tested to 69 lbs.

About 5 feet of the front end of the boiler opened out flat, and was thrown to the rear about 60 yards; the front hemispherical end was liberated and thrown 20 yards also to the rear and right hand. The back part of the boiler was thrown in a mass, and after bounding twice, lodged at a distance of 230 yards.

The cause of the explosion appeared to be from the failure of a seam over the fire place in a plate deteriorated by age, and overheated through a deposit of scurf and mud.

_No. 9. Birmingham. (Fig. 6.) February 7th. 1 killed, 4 injured._

Plain Cylindrical Boiler, with hemispherical ends, 23ft. long, and 5ft. diameter, 3/8 inch plates, 50 lbs. It was set so as to be fired under the bottom if required, but the grate was seldom used. The principal heat was supplied from a mill furnace, the neck of which was at the left hand of the back, and the flame was carried by a wheel flue round the front of the boiler to the stack on the right hand side of the back. The boiler was fitted with a 4-3/4-inch safety valve, and also a float, but it was suspected that the latter had broken from the rod.

A horizontal seam about the middle of the left hand side had given way, and the upper portion of the 3rd and 4th rings of plates had spread out like a lid without being detached from the boiler. The front end became detached and was thrown some distance to the front.

The cause of explosion was, that the left side of the boiler became overheated, and so much softened, that it first bulged outwards with the ordinary working pressure, and then rent open. The overheating was most likely the result of shortness of water, but it might possibly have been in consequence of the intense heat of a mill furnace impinging on a small area so near the water line, leading to such rapid ebullition as to prevent sufficient contact of the water to keep the plates cool.

_No. 10. Dunse. February 14th. 1 injured._

Locomotive. It exploded while standing in a shed, but no particulars have been obtained.

_No. 11. Middlesbro'. February 26th. 1 injured._

Marine, in a small tug boat, but no details have been obtained.

_No. 12. Gainsbro' (Fig. 7) February 26th. 1 injured._

One Tube Cornish, 21ft. long, 5ft. diameter, with one tube 2ft. 11in. diameter, plates 3/8 inch, 64 lbs. There were no strengthening rings on the tube. The boiler was second-hand, and had only worked a part of a day at its new position when it exploded.

The tube collapsed from weakness without strengthening rings.

_No. 13. Redruth. (Fig. 8.) March 3rd. 1 killed._

One Tube Cornish, 31ft. 9in. long, and 5ft. 9in. diameter, tube 3ft. 8in. diameter, 3/8 inch plates, 40 lbs.

The tube had been repaired with a bolted patch on the left side the day before the explosion, and it is presumed it was slightly out of the circular shape, as it collapsed sideways, the top being thrown up above its proper height. There was no evidence of shortness of water.

The tube without strengthening rings was too weak to sustain the ordinary working pressure.

_No. 14. London. March 5th. 7 injured._

Cornish, at 27 lbs., but as the boiler was not injured, it is only noticed as an explosion, because of the imprudence of placing fittings in such dangerous positions. The boiler was beneath a work room, and the lever of the safety valve became displaced, allowing the valve to blow out, and the escaping steam rushed into the room above and scalded seven men very badly.

_No. 15. Manchester. March 6th. 1 killed._

This was a Boiler with two internal fireplaces, connected into one flue at the back.

The crowns of both furnaces were collapsed, and slightly rent, and the escaping steam and water scalded the attendant.

The water was 8 or 9 inches below its proper level, allowing the furnace crowns to become overheated and unable to bear the working pressure.

Each furnace had been fitted with a fusible plug, but they proved inefficient.

_No. 16. Norwich. (Fig. 9.) March 13th. 1 killed, 1 injured._

This was a very small boiler, 8ft. long, and 3ft. 2-1/2in. diameter, with two small tubes. It was fired externally.

The dome was blown off and the rents continuing, the top opened out on each side, and the upper portion of both back and front was bent back.

The dome cut away the whole of the top plate, and so much reduced the strength that it would not bear the ordinary working pressure.

_No. 17. Dudley. (Fig. 10.) March 19th. none injured._

Plain Cylinder Boiler, 36ft. long, 5ft. 6in. diameter, 60 lbs. It had frequently been repaired over the fire, so that the longitudinal seams ran for several plates without break of joint. A patch had been put on a few days before explosion, and as the rivet holes had badly fitted, there had been much strain caused by drifting, and the rivets were much distorted.

A longitudinal seam gave way over the fire, when two rings of plates opened out, rending the transverse seams at each side until completely separated, and fell in two parts at a distance of about 100 yards in front of the boiler. The front end was liberated and fell in one piece about 100 yards beyond the two pieces of the shell. The main body of the boiler was driven back a few yards and rolled over so as to be upside down, but was little injured.

The frequent and badly executed repair over the fireplace, had so weakened the structure as to make it unable to bear the very high ordinary pressure. This frequent repair over the fireplace had been made necessary by very hard firing and deposits of scurf from muddy water, preventing the proper contact of the water with the plates.

_No. 18. Liverpool. March 22nd. 1 killed._

This was a small Boiler to supply steam for some steam winches on board a steam boat, and exploded from the overheating of the upper tubes through shortness of water, or from over pressure in consequence of having only one safety valve.

_No. 19. Leeds. (Fig. 11.) March 27th. 2 killed, 18 injured._

Two Tube Cornish, 24ft. 6in. long, 6ft. 6in. diameter, tubes 2ft. 6in. diameter, 3/8 inch plates, 54 lbs., fitted with steam gauge, blow-off cock, 1-1/2 inch dead weight safety valve, loaded to 54 lbs., and 4-3/8 inch lever safety valve, loaded to 62 lbs., and had been at work about five years.

Nearly the whole of the two back rings of the shell were torn off and opened out, and the boiler was turned partly round, and moved upon its seat sideways and forwards.

There was extensive corrosion at the under side of the back of shell, where the first rent took place, caused by the leaking of the joints and seams.

_No. 20. Swansea. (Fig. 12.) April 4th. 5 killed, 4 injured._

One Tube Cornish Boiler, 30ft. long, and 7ft. diameter, tube slightly oval about 4ft. diameter, 7/16 inch plates, 43 lbs., fitted with 3-1/2 inch safety valve, which is much too small for such a boiler, glass water gauge, two gauge cocks, and pressure gauge.

The tube collapsed from end to end. The front end was blown out with a short length of the tube attached, and was driven against a wall about 30 yards to the front. The main body of the shell, and the back end, with the collapsed tube within it, were driven back against another wall, about the same distance away. Very great damage was done to the surrounding property.

The cause of the explosion was the weakness of the tube of so large a diameter, without strengthening rings, which made it unable to bear the ordinary working pressure. It is very probable, however, that at the time of the explosion, the pressure was considerably more than usual during the stoppage of the engine, and the confusion caused by a man becoming entangled in the machinery.

_No. 21. Morpeth. April 10th. 1 killed._

Plain Cylinder Boiler, 34ft. long, and 5ft. diameter, 3/8 inch plates placed lengthways, 33 lbs.

The explosion took place at a seam in the front part of the bottom of the boiler just over the fire. This rupture allowed the sides to expand, until the boiler was completely destroyed and torn into seven pieces.

The cause of the explosion was supposed to be the defective state of the seams over the fire, which, being placed longitudinally, were in the weakest position.

_No. 22. Shiffnal. (Fig. 13.) April 21st. none injured._

Two Tube Cornish, 15ft. long, 6ft. diameter, tubes 1ft. 8in. diameter, 3/8 inch plates, 40 lbs. The heat was supplied by two furnaces, one of which played into each tube.

The left hand tube collapsed from shortness of water, and tore away from the angle iron in the front plate, and allowed the contents to issue violently and scatter the brickwork, but the boiler was not disturbed.

_No. 23. Burnley. April 26th. 2 killed, 2 injured._

Small internally fired Boiler, 5ft. high, 2ft. 4in. diameter, and was intended to work at 70 lbs. The fittings were defective, the spiral spring of the safety valve being most easily altered, so as to cause over pressure. The manhole was not strengthened by any ring, and the first rents commenced at that point.

The cause of the explosion was over pressure and defective construction.

The sketch at No. 57 explosion in this year, is of a similar boiler which exploded from nearly similar causes.

_No. 24. Bilston. (Fig. 14.) May 13th. none injured._

Balloon or Haystack Boiler, about 16ft. diameter, 5/16 inch plates, and worked at very little above atmospheric pressure.

The boiler was chiefly used to store water during the time another boiler by the side of it was emptied. When the water was required to refill the other boiler, a fire was lighted under the balloon, and sufficient steam generated to drive the water from it into the other boiler. The safety valve never being used, it had become fast, and as a little more steam than usual had accumulated, the bottom gave way, and the reaction of the issuing contents made the boiler rise from its seat, and it fell on its side at some distance away flattened by the fall.

_No. 25. Westbromwich. (Fig. 15.) May 25th. none injured._

One Tube Cornish Boiler, 15ft. long, and 4ft. 6in. diameter, taper tube, 2ft. 9in. diameter in front, and 2ft. diameter at back, 3/8 inch plates, 40 lbs. The boiler rested on two walls forming the bottom flue. There was a safety valve, a glass water gauge, a pressure gauge, and two fusible plugs upon the tube.

Two longitudinal rents took place on the under side of the shell, allowing two strips, forming the central part, to open out by the continuation of the fracture, until they were blown to a considerable distance. The tube with the front end, and one ring of the shell were thrown to the front, while the back end was thrown to the rear, the smallest end of the tube having torn away from the back.

The shell was deeply corroded where it rested on the side walls of the bottom flue, and the strength of the boiler was thereby so much reduced, that it was unable to bear the ordinary working pressure.

_No. 26. Halifax. (Fig. 16.)_ _May 26th. 1 killed._

One Tube Cornish, 24ft. 6in. long, and 5ft. diameter, taper tube, slightly oval in the front, 2ft. 8in. diameter, and 2ft. diameter at the back, 3/8 inch plates. The boiler was fitted with glass water gauge, float, self-acting feed apparatus, and safety valve loaded to 52 lbs., and also a mercury gauge.

The tube collapsed over the fire, a rent taking place in the second ring of plates. The issuing steam and water caused the death of a man in front, but the shell of the boiler was not injured or moved.

The cause of the explosion was shortness of water, and as the glass gauge was set unusually low, the man in charge may have been deceived. The oval shape of the fireplace, and the laminated iron, as shown in the fracture, rendered the tube peculiarly liable to collapse.

_No. 27. Durham. May 26th. 1 killed._

Plain Cylinder Boiler, 34ft. long, 5ft. diameter, 3/8 inch plates, 45 lbs., fitted with two 5-inch safety valves, and 2 floats.

The boiler was torn in two pieces, that were thrown to a considerable distance. The first rent had taken place immediately over the fire.

The cause of the explosion was the weakening of the shell by frequent repair over the fire, rendered necessary by the deposit from the muddy water preventing proper contact of the water with the plates.

_No. 28. Durham. May 27th. 1 killed._

Plain Cylinder Boiler, 32ft. long, 6ft. diameter, 3/8 inch plates, 35 lbs., fitted with two safety valves, two floats, and two alarm whistles.

The boiler was lifted from its seat, and one end was separated and thrown to a considerable distance.

The cause of the explosion was weakening of the shell from repair a few days before, and perhaps over pressure, as the gauge was found some time after, and indicated that the pressure had at some time exceeded 80 lbs.

_No. 29. Redruth. May 28th. 1 killed, 4 injured._

One Tube Cornish, 30ft. 8in. long, 6ft. 8in. diameter, tube, 4ft. diameter, 7/16 inch plates, 40 lbs.

The tube collapsed, and rent, and the issuing steam and water scalded those near, as it was too weak to bear the ordinary working pressure.

_No. 30. Leicester. (Fig. 17.) May 31st. 1 killed, 1 injured._

Plain Cylinder Boiler, with dished ends, and only 4ft. 2in. long, and 2ft. 6in. diameter, 1/4 inch plates. It was most inefficiently mounted, the safety valve was only 1-5/8-inch diameter, and of such faulty construction, that it would not open under a pressure of 162 lbs. There was no steam gauge or float, and the gauge cocks were defective. There was no means of putting water in the boiler when there was a pressure of steam. The manhole was very large for so small a boiler.

Four rents started from the manhole and continued along the top of the boiler and round the end seams. A tongue-shaped strip of the top plate was attached to the back end plate; two strips about a foot wide on either side were blown away. The boiler had been turned nearly round in its flight, and fell with the back about 12 feet from the original position of the front.

The boiler was worked until it was nearly dry, and, during a temporary stoppage of the engine, an accumulation of steam caused a greater pressure than the boiler could bear.

_No. 31. Newcastle. June 7th. none injured._

Marine Boiler in a Tug Boat.

The boiler was blown completely out of the vessel, and the greater part of it fell into the water, and a large piece alighted on a crowded quay, but without doing any damage.

The cause of the explosion was supposed to be over-pressure during a temporary stoppage of the engine.

_No. 32. Barnard Castle. (Fig. 18.) June 11th. 2 injured._

Agricultural, of about 7 horse power. The barrel of the boiler was 6ft. 1in. long, 2ft. 5in. diameter; the fire-box end was 3ft. wide, and 2ft. 4in. deep; the fire-box was 2ft. 5-1/2in. wide, and 2ft. 7in. high, and 1ft. 9-1/2in. deep, with 23 tubes passing from it through the barrel to the smoke box and chimney. The boiler was fitted with a 2in. safety valve, which was intended to blow at 45 lbs., but as there was no ferrule, it is supposed to have been screwed down to a much greater pressure.

The upper portion of the shell over the fire-box rent through the manhole, and allowed the shell to open out and fall on each side. A large portion of the front plate was also torn off.

The cause of the explosion was the weakness of the manhole, which was not strengthened by any ring, and also excessive pressure from want of proper safety valve.

_No. 33. Breage. June 11th. 1 killed._

Cornish Boiler, 36ft. 6in. long, and 6ft. diameter, 3/8 inch plates, 45 lbs.

The tube collapsed and rent, and the issuing contents caused the death of the attendant.

The weak tube of such large diameter, was unable to bear the ordinary working pressure, having no strengthening rings.

_No. 34. Nottingham. June 19th. 2 killed, 4 injured._

Locomotive, 1/2 inch plates, 140 lbs.

The explosion occurred at the left hand side of the ring of plates in the barrel next the fire-box, and below the foot-plate. The rent tore along the edge of the lap and into the next ring of plates. The reaction of the issuing contents threw the engine off the rails.

The cause of the explosion was partial corrosion at the point of rupture and strain of the plates, as the boiler itself formed part of the frame of the engine.

_No. 35. Richmond. June 26th. 2 injured._

Locomotive, being tried for the first time. The funnel came in contact with a bridge, and the dome was also torn off.

_No. 36. Gainsbro' June 29th. none injured._

No details have been obtained.

_No. 37. Durham. July 2nd. 4 killed._

Plain Cylindrical Boiler, 30ft. long, and 6ft. diameter, 3/8 inch plates, 28 lbs. It had been repaired a short time before the explosion, with 5 new plates.

The boiler was torn up into several pieces, but the main portion remained flattened out on the seating, while some smaller pieces were sent 250 yards away.

The cause of the explosion was the deterioration of the boiler, and its frequent repair over the fireplace.

_No. 38. Liverpool. June 12th. 4 injured._

Elephant Boiler, 20ft. long, and 4ft. diameter, 3/8 inch plates, and worked at low pressure. The bottom shell had a tube through its whole length.

A rent took place in the lower part of the fireplace, and extended along the bottom, and the reaction of the issuing contents caused the top to rear up.

The cause of the explosion was supposed to be that the bottom plates were worn too thin to bear the ordinary pressure.

_No. 39. Sheffield. July 4th. none injured._

Two Tube Cornish Boiler, externally fired, 30ft. long, and 6ft. diameter, 3/8 inch plates, 40 lbs.

The second seam over the fire gave way, and the plate sank down upon the fire.

The cause of the explosion was the deterioration of the seams over the fire, in consequence of the deposit of scurf which could not be properly cleared off owing to the internal tubes.

_No. 40. Oldham. July 14th. none injured._

Boiler, with two internal furnaces, 9ft. 6in. long, and 2ft. 11in. diameter, 3/8 inch plates, uniting into one tube beyond. The furnace crown collapsed near the front of the boiler.

There was an extra weight upon the safety valve, and the steam valve was left closed, so that more pressure accumulated than the boiler could bear.

_No. 41. Oxford. July 23rd. 3 injured._

Rag Boiler, not used for the generation of steam. It was a plain cylinder, with hemispherical ends, about 16ft. long, and 7ft. diameter. There was a neck at each end upon which the boiler revolved, and through one of these the steam was admitted to a pressure of 30 lbs., in order to assist in cleaning the rags. There was a large manhole for filling and emptying.

The boiler rent in the middle, and each half was blown to some distance.

The manhole was so large, that the strength of the boiler was too much reduced, and the constant strain of revolving caused a central seam to give way at the ordinary pressure.

The sketch to No. 63 is of a similar boiler.

_No. 42. Tunstall. (Fig. 19.) July 28th. 2 killed, 7 injured._

Boiler, 36ft. 6in. long, and 8ft. 9in. diameter, 7/16 inch plates, with flat back and hemispherical front end, 36 lbs. A tube 3ft. 3in. diameter, passed from the back end nearly to the front, and returned to the back end, but of 6 inches less diameter and then passed to an iron chimney. The fire grate was beneath the hemispherical end.

The angle iron of the flat back end gave way, and separated from the shell and with the tubes attached was blown to a good distance, and the reaction drove the shell far in the opposite direction.

The cause of the explosion was the bad construction of the boiler, as the back end was quite unsupported, as there were no stays, and the bend of the tubes was not attached to the shell.

An adjoining boiler which was being cleaned inside by two men, was rolled off its seat by the force of the explosion.

_No. 43. Widnes. August 2nd. 2 killed, 6 injured._

Plain Cylindrical Boiler, with flat ends, 23ft. long, 5ft. 3in. diameter, 3/8 inch plates, 40 lbs.

Both the flat ends were blown out, and the first ring of plates at the front end torn off.

The cause of the explosion was the weakness of the flat ends without stays.

_No. 44. Sunderland. August 7th. 1 killed, 3 injured._

Locomotive, 13ft. 4in. long, 3ft. 11in. diameter, with 140 2-in. tubes. The fire-box was 4ft. 5in. long, 3ft. 6in. broad, and 5ft. deep, and made of copper, 1/2 inch thick, 100 lbs. It was fitted with two 4-in. safety valves, and a steam gauge.

The fire-box gave way about the middle of the left side, 2ft. 6in. below the water line, where corroded to 1/8 inch, and the issuing water and steam scalded those near.

_No. 45. Runcorn. (Fig. 20.) August 22nd. 3 killed, 5 injured._

Marine Multitubular, 5ft. 8in. long, and 6ft. 6in. diameter, with two internal tubular furnaces, which joined to an internal chamber of large size, and small tubes passed to a smoke box and chimney in the front over the fire doors. Both ends were flat.

The flat back end was insufficiently stayed, and was blown completely out and torn into two pieces, the lower portion remaining in the vessel, and the upper part falling in the water, and the reaction of the issuing contents caused the boiler to be thrown on to the side of the quay.

_No. 46. Hull. (Fig. 21.) August 25th. 1 injured._

One Tube Cornish, 24ft. 3in. long, and 6ft. diameter, taper tube 3ft. 5in. diameter, for about 7ft. 6in. in length, and 2ft. 6in. diameter for the rest of the length, 33 lbs.

The tube was much corroded, and the fireplace gave way on left side, and was so much torn, that the plates were forced out of the front.

_No. 47. Morecombe. August 27th. 3 killed, 1 injured._

Marine, of the usual construction, and had been tested to 60 lbs.

It gave way at the lower portion of the back, and the issuing steam and water scalded those near.

A seam rent, 6ft. 6in. long, had not been detected by testing.

_No. 48. Tuddenham. August 29th. 2 killed, 2 injured._

Agricultural. It burst during a temporary stoppage from accumulation of steam, causing undue pressure.

_No. 49. Glasgow. August 31st. 3 killed, 6 injured._

Upright Boiler, 36ft. high, 5ft. 6in. diameter, 7/16 inch plates, 45 lbs.

The bottom gave way from shortness of water, and the main bulk of the boiler was thrown straight up into the air to a great height, but descended again on its seating.

_No. 50. Chatham. (Fig. 22.) September 7th. 2 killed, 30 injured._

Two Tube Cornish, 22ft. long, 7ft. 6in. diameter, with tubes, 3ft. diameter, 7/16 inch plate, 60 lbs.