The annexed engravings show several improvements in Steam Boilers, and the application of the waste steam or waste hot-air of hot-air engines for additional service. The first-named improvements refer to the inter-nalconomy of the boiler, and consist in substituting for the tubular parts of boilers bent sheets of iron, which serve as partitions between the water spaces and the flues through which the hot-air, smoke, and flame pass. Fig. 1 is a longitudinal section through the dotted line, r s, fig. 2, in which F is the furnace, D the door, C the chimney, S the space for the water and steam above the flue; in n shows the upper part of the partition plate in* sectionthe direction of the flame and hot-air from the furnace up the chimney being denoted by the arrows. Figure 2 is a sectional view showing the disposition of the flues and water spaces. The boiler consists of a cylindrical shell, within which is another shell, ionKtinj? pttrt of * yttRtiw. the space between the two, np ?, figs. 1 and 2, being filled with water, and also strengthened with stays at nfo' o", fig. 2. The inner shell at a and A, fig. 2, is secured steam tight to the plate forming the partitions, which is curved at a c bfc g d, fig. 2, thus alternate water spaces and: narrow flues are formed. Bars of iron, xx x, \ figs. 1 and 2, are secured between the flues at i short intervals apart, and run lengthwise in j the boiler as shown in fig. 1 ; these serve two ! purposes, one is to strengthen the sheets of a perfect cylinder, the object ot making the space between the two, and filling it with water, being only to form a kind ol jacket to prevent the loss of heat. Figure 3 is a design for another boiler of a somewhat different construction, and exhibits a novel arrangement of the water spaces and flues. Within the outer shell are placed several other circular shells, whose common centre is below that of the exterior one, the spaces for the water are marked w, and those for the heat k. Between the inner shells are placed at intervals small pieces of iron, 252c, which serve to support and keep them in then-proper position. The communication between the water spaces is maintained by the open space, T, and a similar arrangement may be made below the centre of the boiler. With iron, which act as partitions, and the other to abstract and retain more effectually the heat that passes through the flues. The water spaces likewise below the line, a h, fig. 2, have narrow iron plates, o o, secured between the partitions, which run at right angles to the direction of the bars in the flues being vertical so as to allow the heated particles of water to ascend without obstruction. They are placed at short intervals and extend only part of the way to the bottom of the water spaces so as to allow the water to circulate freely below them, and for this purpose they may be perforated with holes or their connection broken at different parts. The boiler, as already mentioned, consists of two distinct shells, the space between them serving as a water-jacket but if required the inner shell can be continued along the dotted line, o A, fig. 2, and thus form the exception of the partial breaks of the tube, T, and ot the supporting pieces of iron, 252c, which are short, the space between the shells is open from end to end of the boiler. Fig. 4 is a design for a heater, intended to turn to further account the waste steam or the hot-air after being used of a hot-air engine, it consists of a number of concentric shells, h hl containing the steam or heated air, the alternate spaces, a a, between them, being filled with the air that it is required to heat. Between these shells or spaces are placed bars, 252c, which extend from end to end of the heater, not however in a straight line, but widening in a spiral form. By increasing the number of the bars the power to abstract and conduct the heat, is augmented, and the same object is effected by increasing the number of the shells. Further particulars respecting these inventions can be known by addressing the inventor, Wm. Henry Morrison, Indianapolis, Ind.