A course or two above the lintel of the door that leads to the condenser, build into the wall two parallel flat thin bars of iron equally distant from each other, and from the outside and inside of the wall, and reaching the whole breadth of the lever wall.

The cold water round the condenser will condense some of the steam contained in the eduction pipe, and its place will be supplied by some of the air from the cylinder.

When that is the case shut all the valves, and observe if the vacuum gauge shows a vacuum in the condenser; when there is a vacuum equivalent to three inches of mercury, open the injection a very little, and shut it again immediately; and if this produces any considerable vacuum, open the exhausting valve a very little way, and the injection at the same time.

AIR PUMP AND CONDENSER.

It expands again to its former bulk on the return of the pump piston, and prevents the water from entering until there is such an accumulation of pressure in the condenser as forces the water into the pump, when the air being expelled by the water, causes a good vacuum to be momentarily formed in the pump when it gorges itself by taking a sudden gulp of water.

So soon, however, as the pressure falls in the condenser and some more air leaks into the pump, the former imperfect action recurs and is again redressed in the same violent manner.

Sometimes one end of the pump will alone draw and the other end will be inoperative, although it is equally open to the condenser, and this will chiefly take place at the stuffing box end, where a leakage of air is more likely to occur.

The injection water is generally admitted to the condenser by means of a slide valve, but a cock appears to be preferable, as it is more easily opened, and has not any disposition to shut of its own accord.

There is but one air pump, which is situated within the condenser between the cylinders, and it is wrought by means of a crank in the intermediate shaftthis crank being cut out of a solid piece of metal as in the formation of the cranked axles of locomotive engines.

The steam enters the cylinder through the outer trunnions, or the trunnions adjacent to the ship's sides, and enters the condenser through the two midship trunnionsa short three ported valve being placed on the front of the cylinder to regulate the flow of steam to and from the cylinder in the proper manner.

The framing consists of an upper and lower frame of cast iron, bound together by eight malleable iron columns: upon the lower frame the pillow blocks rest which carry the cylinder trunnions, and the condenser and the bottom frame are cast in the same piece.

A.The condenser, which is cast upon the lower frame, consists of an oval vessel 22-1/2 inches wide, by 2 feet 4-1/4 inches long, and 1 foot 10-1/2 inches deep; it stands 9 inches above the upper face of the bottom frame, the rest projecting beneath it; and it is enlarged at the sides by being carried beneath the trunnions.

A.The air pump, which is set in the centre of the condenser, is 15-1/4 inches in diameter, and has a stroke of 11 inches.

The mouth piece and the air pump barrel are made tight to the condenser, and to one another, by means of metallic joints carefully scraped to a true surface, so that a little white or red lead interposed makes an air tight joint.

The lower frame is not set immediately below the top frame, but 2-1/2 inches behind it, and the air pump and condenser are 2-1/2 inches nearer one edge of the lower frame than the other.

Q.Will you describe the nature of the communication between the cylinder and condenser?

A.The pipe leading to the condenser from the cylinder is made somewhat bell mouthed where it joins the condenser, and the gland for compressing the packing is made of a larger internal diameter in every part except at the point at which the pipe emerges from it, where it accurately fits the pipe so as to enable the gland to squeeze the packing.

A.The pipe leading to the condenser from the cylinder is made somewhat bell mouthed where it joins the condenser, and the gland for compressing the packing is made of a larger internal diameter in every part except at the point at which the pipe emerges from it, where it accurately fits the pipe so as to enable the gland to squeeze the packing.

By this construction the gland may be drawn back without being jammed upon the enlarged part of the pipe; and the enlargement of the pipe toward the condenser prevents the air pump barrel from offering any impediment to the free egress of the steam.

The eduction pipe is attached to the condenser by a flange joint, and the bolt holes are all made somewhat oblong in the perpendicular direction, so as to permit the pipe to be slightly lowered, should such an operation be rendered necessary by the wear of the trunnion bearings; but in practice the wear of the trunnion bearings is found to be so small as to be almost inappreciable.

It is not expedient to cast the trunnion plummer blocks upon the lower frame, as is sometimes done; for the cylinders, being pressed from the steam trunnions by the steam, and drawn in the direction of the condenser by the vacuum, have a continual tendency to approach one another; and as they wear slightly toward midships, there would be no power of readjustment unless the plummer blocks were movable.

A.The bottom frame, on which also the condenser is cast, forms the base of the engine: on one end of it the cylinder is set; on the other end are the guides for the cross head, and in the middle are the bearings for the crank shaft.

The air pump is bolted to one side of the bottom frame, and a passage is cast on it conducting from the condenser to the air pump.

The passage communicating between the condenser and the top of the balance piston was too small, and the pins at the ends of the link connecting the valve and balance piston were formed with an inadequate amount of bearing surface.

The beam of light is furnished by three gas-burners, and it passes through a condenser.