will cause the air to pass with great velocity through the pipe across the smoke chamber, and through the tubes leading from the smoke chamber to the fire box, and into the tubes placed in the fire box. By passing through these last mentioned tubes, which will be highly heated, the atmospheric air will become also heated, and when mixed with the combustible gases within the fire box will cause a much more perfect combustion of the smoke and gases than could take place without the introduction of fresh atmospheric air. By this arrangement of introducing heated air in connexion with the peculiar form of fire box, whereby more space is given for combustion, and a consequent better mingling of the oxygen with the gases, coal may be burned without inconvenience from smoke, in locomotives, thereby causing great economy in fuel. It is usually intended to make the prolongation of the fire box cylindrical in form, and to prevent it from crushing by external pressure it may be made corrugated, as shown in section, sheet 6, figure 6; by this means, all stays between the inner and outer cylinders may be dispensed with, excepting a few to support the inner cylinder in its place.

Stationary or Chimney Boiler.-This is an arrangement of boiler, as shown in sheet 5, figures 1, 2, and 3, which is intended to accomplish a more perfect combustion of the fuel used, and a consequent consumption of a greater portion of the smoke, and at the same time, to dispense with the very expensive towers now used as chimneys. Figure 2, sheet 5, shows a vertical section of chimney boiler; it is made of circular form throughout, for more facility in making, and for greater strength, although it may be made of any form deemed most advisable. The flame and combustible gases from the fire box or furnace, A, ascend, and in part pass off through the flues, в, seven in number, as shown in figures 1, 2, and 3, and through the three smaller flues, c, figure 3. The remaining portion of flame, &c., pass from the fire through the short flues, D, figure 3, into the upper chamber of boiler, as shown in figure 2, coming in contact in their passage to the top of the boiler with the external surface of the seven vertical tubes, through which the flues, B, pass, as well as in contact with the three vertical tubes through which the flues, c, pass. The flame and gases, after they reach the top of the inner chamber of the boiler, are carried out to the external air through a series of small flues leading from the roof of the interior chamber to the extreme top of the boiler. For a more perfect combustion of the gases in the upper chamber, a series of jets of pure air may be admitted at convenient points through the outer diameter of boiler. It is intended to surround the boiler with a casing, leaving a small space between it and the exterior surface of the boiler. The air being taken from the space just mentioned will be partially heated before entering the boiler, and consequently better adapted for aiding the combustion of the gases which may have passed off from the fire into the upper chamber. At any part of this boiler, either in the fire place or upper chamber, where a stay may be needed for connecting the inner to the outer plate, it is intended to put one of the tubular stays heretofore described, unless there should not be room for the projecting end. Sheet No. 9 shows another modification of the chimney boiler. In this case the boiler has a clear passage to the external air at the top. It is made circular in form for greater strength; the

form, however, not being deemed essential, with an enlargement of the top for steam room. To absorb heat from the flame and gases which pass upward from the fire, the interior of the boiler is studded with tubular stays, so arranged as to bring the greatest amount of fire surface in contact with the flame, previously to its reaching the top of the boiler. This chimney boiler may be made square or oblong in its cross section, in which case the tubular stay may be used for increasing fire surface, or if necessary, the whole interior may be filled with cross tubes filled with water. In like manner, the boiler, if of circular form, may be filled with cross pipes, disposed as may be most convenient for accomplishing the desired end. The chimney boiler is intended to be put together with bolts at bottom, so that the interior may be taken. out if necessary, for repairs, or for cleaning interior surface from mud, &c. In the foregoing description of various forms of boiler, it will be manifest that an effort is made to apply the main portion of heat to the external surface of tubes filled with water, instead of allowing the flame and gases to pass through small tubes, as is now generally used in locomotive as well as marine boilers. It is very obvious that the more the combustible gases evolved by the fire are kept in connexion, the greater the chances of active combustion; whereas, by a very simple experiment, it will be found that combustion cannot be kept up to any great extent in a small tube, say from 1 to 2 inches diameter, except for two or three feet after the flame first enters from the fire place. Beyond four or five feet, it is very doubtful whether it is worth while to carry the dead weight of tubes which are now used in the boilers of locomotive engines. By putting water inside the tubes instead of around them, the mass of combustible gases are connected together by being distributed between the tubes, and thereby a better combustion takes place, which may be to a great extent improved by letting in atmospheric air into the fire box above the fire and amongst the tubes in the manner heretofore described in this specification, chapter 2d.

Figures 1 and 2, sheet 4, show a second time the mode of putting on the back sheet of fire box with screw bolts, and planed surface or packed joint, so that it may be taken off at pleasure, by taking out the stay bolts, which give greater facility for repairs and cleaning, whilst at the same time it permits the entire fire box to be taken out as soon as the stays and the series of small flues leading to smoke chamber are removed, whenever these flues are used. Sheet 6, figure 7, shows in red lines, a mode of protecting the upper surfaces of the tubes or other portions of the boiler which contain water, and in which, from the great quantity of steam bubbles which may be thrown against these surfaces, there is danger of the water being driven away from them, causing these portions to be thereby burnt. To remedy this evil, I cause to be placed in the upper portion of each tube containing water, or at any other point where the same difficulty is likely to arise, a thin metal shield, curved in such a manner, and fitting so closely as to intercept a great portion of the ascending steam, and leading it off towards the end of the water tube, or in other portions of the boiler not tubular, away from the points of fire surface, where danger might be apprehended by the water being driven

away. By extending these shields through the entire length of the water tube, and through to the front tube sheet at the smoke box, and by perforating the curved surface of the shield with holes, the steam will be discharged in rapid currents upwards, and between the series of flues leading from the fire box to the smoke box, which current will tend in a great degree to keep the flues just mentioned, from being coated with mud, or other incrustations.

What I claim as my invention in the above described specification, and which I desire to secure by letters patent, is as follows:

Firstly. In extending the fire box into the boiler in the manner hereinbefore in this specification, and by the said drawings, substantially described.

Secondly. In connexion with such extension, the placing in the fire box and extension thereof, a series of horizontal, vertical, or diagonal tubes or pipes containing water, and either using the ordinary flues much shortened, (thereby saving useless weight,) leading from the fire box to the smoke chamber, or not, as may be deemed best, arranging the parts in the manner described, or in any other manner substantially the same as hereinbefore and in the said drawings described.

Thirdly. The using and adapting the "teats," well known to boiler makers, in such manner as to form tubular stays of cast or wrought iron, or any other metal for obtaining fire surface in the fire box, or any other part of a steam boiler, and at the same time making a secure connexion (easily removed) between the inner and outer plates of boiler, as substantially herein before described, and more particularly shown in figure 5, sheet 1.

Fourthly. The applying tubes or pipes of any given diameter, filled with water above the fire in the fire box of locomotive or other boilers now in use, and as they are now generally made, substantially as hereinbefore described, and more particularly shown in drawings on sheet No. 2.

Fifthly. The use of return flues leading through the horizontal water pipes, as described in marine boiler, as well as the inner flues leading through the water tubes of locomotive boiler, to carry off a portion of the gases to the smoke chamber, so as to present a double heating surface to the water contained in the water tubes, whether these flues are made to pass through the whole length of water tube or not, or made so as to receive the gases at any point throughout the whole length of water tube, substantially as herein before described, and more particularly shown in sheet No. 7.

Sixthly. The construction of the chimney boiler, substantially as hereinbefore described in drawings 5 and 9, including the various modes of obtaining fire surface by the use of vertical water pipes with or without inside flues through them, or by filling the interior chamber above the fire, with "teats," serving the double purpose of giving fire surface, and making a secure stay, or with cross pipes, either in connexion with the short flues at top of boiler, or not, described and shown in drawings. Nos. 5 and 9, as may be deemed best, and not confining myself to any particular form of boiler or mode of arranging said pipes, flues or tubular