Mr. Webb. less and less. He had been trying to wear out one engine, which he started two years and seven months ago to take an express train every day from London t o Manchester and back. During that time it had run over 300,000 miles. The last time he took the tubes out, the box was getting thin, and he was obliged to put in a new one; but the boiler itself, in which zinc had been used during the whole time, was apparently as good as on the day when it went out of the shop, and he hoped to get 300,000 miles more out of ii.. A circular piece of zinc was put in the Scale h.mud-pocket under the barrel. The scale was of a blue colour, showing that the zinc was incorporated with it to some extent. The fire-box was of copper. He had tried steel fire-boxes for locomotives, and could go on using them, but not with commercial
133to patch fire-boxes, as special bolts for screwed patches were there Mr. Webb. advertised. The method of staying fire-boxes on the London and North-Western Railway was shown in Fig. 12.Paper to the use of collapse-rings, and credit had been given. to two or three engineers in connection with them. He thought that the name of Sir W. Fairbairn ought to be mentioned, seeing that those rings grew out of the special researches made by him. The form commended by the Author was that originally adopted, and the first was made about twenty-two years ago. His opinion had been asked with regard to putting rings round the flue, without attaching them to the flue, and the subject had been mentioned in the Paper. Some engineers had the ides that if they .simply made a true circular ring and slipped it on a flue, it would have the same effect as a ring riveted to the flue, and their .argument was, that before the flue could collapse, it must be distorted, and as the ring prevented distortion, it prevented collapse. That was a most dangerous way of proceeding. H0 had seen flues collapse, and his impression was that there was no necessary distortion of the circular form previous to this taking place. He had caused glass cylinders to collapse, and there of course no distortion could occur. In the Author's observations about the placing of the material of the boiler with the fibre in the direction of the greatest strain, he ought to have restricted himself to iron, because there was nothing like the same difference in steel.hear Mr. Webb's opinion with reference to the roof-stays of the locomotive boilers on the London and North-Western Railway. Some persons, like himself, still adhered to roof-stays. If they were properly applied with sling-stays from the circular top of the boiler they were much better than a *quare covering. Screwstays' for a locomotive-boiler with a square top were very difficult to get at, especially for repairing. As far as his experience went, the crown of the boiler, if provided with properly made roof-stays, did not give way; the fire-box tube-plate, the front plate, and even the side plates, would give way before the crown plate. The Author had not given any taper to the fire-box of th...
