to damage it or its seat, fill the boiler with clean water, put in the boiler the usual quantity of Naenaires Anti-Corrosion liquid, or the powder, make the manhole joint with plaited three-strand spun yarn and stiff putty (red lead and white lead) and lay the fire, which is done in this way: throw a dozen shovelfuls of coals towards the bridge, and to left and right of it till they reach near to the dead-plate, leaving the centre clear for the firewood; then throw in three or four shovelfuls of coals over the wood, with oily waste or paper in front, and she is ready for lighting, and the "fire is laid." The material for the bridge and the flue ports are firebricks and fireclay; these are rather expensive, but I learnt a wrinkle in the building up of bridge and flues. Through the frequent removals of these for boiler inspection and the hitting of the end of the long poker, several bricks were broken every three months, and I came to the decision to try stock bricks faced with fireclay as mortar; and I was more than satisfied with the result, and ever since then I used stock bricks and fireclay only.

14. Question.—How high should the top of the bridge be from the crown of the boiler or from the fire-tube?

Answer.—The bridge should be about nine inches from the crown of the fire-tube, if it were eight the draught would be curtailed, if it were ten the draught under the bars would be diminished, through much air passing over the bridge instead of under the firebars. As I had permission from my employers to build the bridge to the best advantage for myself in keeping up the steam, and having tried different heights for many years, I found that nine inches was the nearest to perfection. And in these experiments two additional bridges were built in one boiler; six feet behind the ordinary bridge was a concave bridge and six feet behind that was a convex bridge. The concave bridge was built close up to the bottom of the fire-tube, and resembled a small archway, and extended down to within nine inches of the bottom or shell of the fireplace; the convex bridge was built on the bottom of the shell and reached to within nine inches of the fire-tube. When the flame from the furnace shot over the ordinary bridge, it clashed down under the concave bridge, then rose up and swept through the convex bridge and away to the bottom flues; the object of these three bridges, in one tube and for one fire, was to keep the flame and heat in the boiler as long as possible, instead of the heat flying swiftly over the bridge and out of the boiler. This experiment seemed to answer very well, but as there were several other boilers connected with this one there was no opportunity of testing it correctly, but the three bridges remained established, and were frequently shown to engineers and others.

15. Question.—What advantage is there in having the blow-off pipe of a boiler entering it from the top instead of at the bottom?

Answer.—I am not aware of any advantage in it, but I am aware of a disadvantage in it, and it is this, that while the boiler is being blown right out for the purpose of cleaning, or other reasons, the stoker will often commence doing some other work, and in due course the boiler is filled up with water, and the fire lighted, and by-and-by the stoker comes to see what progress she is making; he looks at the water-gauge but sees no water in it because it has syphoned out of the boiler; at first the heated air pressed on the water and forced it through the blow-off pipe, and then the pipe became a syphon, and the pressure increasing as the water leaves the boiler, she is soon emptied, and if the fire is not raked out, soon burnt. Such a mishap could not happen to a boiler with the blow-off pipe at the bottom, for when the stoker blows out his boiler he must shut the cock before he can fill her, and when filled there is no chance of the water escaping out again.

16. Question.—Is there not some disadvantage in having the blow-out cock at the bottom of the boiler?

Answer.—Yes; the cock and pipe are subject to corrosion on account of water dripping down on them from the stoke-hold floor, as some stokers quench their clinkers and ashes while they are up against the front of the boiler, instead of drawing them forward a few inches from the front: and as the pipe is out of sight under the plates of the floor, nobody takes the trouble to lift them and examine—not only the pipe and the cock, but that part of the boiler where the water streams down from the drenched ashes so frequently. So there are disadvantages in both methods of blowing out the boiler, and always will be, until the stoker learns his business, and takes an interest in his work, not only for his own sake, but his employer's also.

17. Question.—What is the most important appendage to a steam boiler?

Answer.—The safety-valve, but it is not always a safety-valve, when it is weighted to twice the amount the boiler is certified to be worked at safely. As an instance: Amongst the many engines employed at the Midland Extension Works, St. Pancras, was a light steam crane for hoisting earth from the deep excavations, there were in use small wooden skips, and the pressure of steam was forty-five lb.; but after a time there arrived large iron skips that the crane could not lift, even when empty; there were about twenty men depending on the crane for their work and the navvy-ganger was anxious for "something to be done," and the crane man hinted about weighting the safety-valve, and no sooner said than almost done; the safety spring balance was screwed down, and a railway chair suspended from it by strong copper wire, and the steam allowed to rise until it reached ninety lb. on the inch, and the big iron skips were hoisted with their load of heavy ballast as easily as the wooden ones had been. The boiler happened to stand it.

18. Question.—Have you any other instance?

Answer.—Yes; in an establishment in Hammersmith some years ago, the stoker was in the habit of putting a bit of iron on the end of the horizontal lever of a safety valve when the steam rose too high, and the manager was about, and when it went down he would take off the bit of iron and put it where he could find it for the next occasion. The manager had gone away one day, and advantage was taken of it to have a little carouse in which most of the men took a part; and when the steam rose the stoker popped his bit of iron on the lever and all was quiet for a time, when another noisy safety-valve began to blow off, and on went another bit of iron that stopped the noise, and during all this time the fires of seven or eight boilers were burning fiercely, and the stoker should have checked his fires instead of what he had done; but in the midst of the carouse all the boilers began to belch forth steam when the manager came on the scene. The stoker tried to pick off the bits of iron before the manager could see them, but the steam was to high for that; and when at last the noise subsided and the steam had cleared away, the whole of the revellers were on view, caught in a trap, as there was only one exit. Most of the men were fined or suspended, the bits of iron were discovered on the levers, and the stoker had a week's notice to clear out, and lock-up valves were fitted on every boiler and the keys kept in the manager's desk ever after.

19. Question.—Can you always depend on the safety-valve lifting when the steam rises?

Answer.—I always keep an eye on the pressure gauge, and if I find that the