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When I was there in 1882 and 1883, we carried 19 pounds pressure, and made 19 revolutions per minute and about 10 knots speed. At this time, and dating back to 1858 when she was built the GREAT EASTERN was the largest vessel afloat, of about 32,000 tons displacement. She retained this position until 1901 when her displacement was exceeded by that of the Crpric and CELTIC of the White Star line, which were of about 38,000 tons displacement. The GREAT EASTERN was a wonderful vessel, but unfortunately ahead of the time when the economy of machinery and the amount of business could make such a big ship pay. Cylindrical Boiler in Use There were still in use many box boilers, that is, boilers with flat sides and depending entirely on bracing for strength, in the older vessels with simple engines, but for compound-en- gined ships the cylindrical or scotch boiler was generally used and con- tinued the favorite for many years. Indeed, there are people today who do not seem to have heard that there is anything better, in spite of the extended use of water-tube boilers for the past thirty years. Freak boilers of various kinds were used _ occa- sionally, such as flat-sided boilers with semi-cylindrical tops and bottoms to enable the space to be utilized more fully, but these soon disappeared in favor of the truly cylindrical boiler. It was about this same time that a momentous change in materials of engineering began to appear, in the substitution of mild steel for wrought iron, both for boiler plate and for engine forgings. Great skill had been acquired in the manufacture of the wrought iron materials, for which the manufacturers deserve great credit, but, when mild steel was developed so as to be reliable, its many advan- tages caused it to displace wrought iron entirely. Some have maintained that boiler tubes of wrought iron are superior to those of mild steel, but the fact is that today the vast majority of the boiler tubes are made of mild steel. Just here, it is worth while to comment on an experience in the early days of mild steel which should be a warning to engineers not to neglect peculiar conditions which appear or to deny their possibility, but to endeavor to ascertain the cause and either remove or avoid it. The new material was received with en- thusiasm, it was assumed that any- thing could be done with it and that it could withstand almost any kind of treatment. . Very soon raysterious failures of sheets and forgings appeared and caused the most serious apprehension. Careful investigation showed, however, that these troubles were due to working the material at what was known as “blue heat,” the name explaining the condition. When this was realized and this particular range of temperature avoided, the troubles ceased entirely. While mentioning the great im- provement in materials, it is im- portant also to note that there had been gradually a great improvement in workmanship. This permitted higher piston speeds and revolutions per minute to be attained, particularly the latter, which was one of the big elements in the reduction of weight. I well remember that in my early days it was assumed as a matter course that bearings were almost sure to Capt. W. M. McFarland overheat at times so that provision was made for the application of a spray of cooling water. When it was possible to get the benefit of the im- provement in workmanship, including alignment, the necessity for this appli- cation of cooling sprays almost en- tirely disappeared, although they are fitted as a precaution. In the early days of the compound engine it was not thoroughly ap- preciated that the increased economy was due, not so much to higher pres- sures and increased ratio of expansion, as to. dividing the expansion into two stages, so that the range of temperature in a_ single cyl- inder would be greatly reduced. Even that standard work, Rankine’s “Steam Engine,” as late as the edition of 1878, contained this statement: “The economy due to expansion is entirely independent of the number of cylinders and will be the same with the same ratio of expansion whether MARINE REVIEW—July, 1928 that takes place in one, two or a dozen cylinders.” Experimentation and study showed that this was entirely erroneous. With the improvement in materials and the possibility of carrying higher pressures, the next step was really obvious, namely, to have expansion in three stages instead of two, which meant the triple expansion engine as a further step in progress beyond the compound. There is some dis- pute as to the credit for the introduc- tion of the triple expansion engine, but usually it is considered that the placing of a set of triple expansion en- gines in the ABERDEEN by Dr. A. C. Kirk of R. Napier & Co. of Glasgow, about 1882, was the real beginning. By this time the theory of multiple ex- pansion was understood and_ there- after the triple expansion engine with pressures up to 200 pounds took posses- sion of the field. ‘These were built in some cases of very large size. Just as was the case with the large com- pound engines, the low _ pressure stage was divided between two cyl- inders, thus making a four cylinder engine. There was a further exten- sion of the principle into the expan- sion in four stages, or quadruple expansion engine, with pressures up to 250 pounds. Some _ of_ these were built, but about the same time the steam turbine began to show its merits, so that their number was never very great. In 1880, a little boat called the ANTHRACITE was built by Loftus Perkins, an American long resident in England, which carried 500 pounds pressure to work with triple expansion. This was so much ahead of practice at the time that nothing came of it and we are only now, fifty years later, begin- ning to use such pressures in ma- rine practice. Naval Requirements Help Progress The favorite boiler with the triple expansion engine was the scotch or cylindrical type, both single and dou- ble ended. The double-ended boiler was of course lighter than two sin- gle-ended boilers of the same amount of heating surface and for large in- stallations was universally used. The machinery for naval vessels has al- ways had one marked distinction from that for merchant vessels, in the vital necessity of keeping weight at a minimum. This was particularly the case in the class of vessels which de- veloped after the invention of the Whitehead torpedo with its own ma- chinery operated by compressed air. To get the full benefit of the tor- pedoes it was necessary to have them launched from very swift vessels of small size. Accordingly the engines 49