Having presented a great number of engravings of boilers in our last volume, and also a great amount of information on this very important subject, we present the following engravings of the "egg-shaped boil- er," much used in some parts of England. A description and diagram appeared in a communication in the last number of the " London Artisan," by Robert Armstrong, the author of the best work ever published on .steam boilers. This boiler is well adapted to be worked by the waste heat of puddling furnaces in iron works, and for this purpose it was originally contrived. Two boilers of this description, 9 feet in diameter and 18 feet high, in an iron works at Wolverhampton, England, made steam sufficient to work an engine of 80 horse power from the spare heat proceeding from four puddling furnaces—two furnaces to each boiler. Figure 1 is a vertical section, and figure 2 a plan view. The arrows show how the heated gases are admitted by the flues, a bed, from the puddling furnaces. These meet at the centre, and pass down and out through the vertical flue, the greatest heat being-applied nearest to thesunace of the water, the correct principle. Having presented a new puddling furnace in the last number of the Scientific American, and having stated in describing it, that it was especially adapted for using waste heat for raising steam to work the engines, this boiler will iorm a useful accompaniment to the same.