Q.An additional slide valve is sometimes used for cutting off the steam? A.Yes, very frequently; and the slide valve is sometimes on the side or back of the valve casing, and sometimes on the back of the main or distributing valve, and moving with it.

Overhead the dark and bulky cylinders cut against the reflected glimmer on the skylights; below, valve-gear and connecting-rod flashed across the gloom, and the twinkling cranks spun in their shallow pit.

35.] A.Stephenson connects the ends of the forward and backward eccentric rods by a link with a curved slot in which a pin upon the end of the valve rod works.

diameter, placed in Bury's locomotive at the apex of the dome, and in Stephenson's upon the front of the boiler, a few inches below the level of the rounded part; and the cover of the man hole in Bury's engine contains the safety valve seats.

The prominent peculiarity of this pump is its valve motion.

The spindles of these valves should project through stuffing boxes in the covers of the valve chests, and they should be balanced by a weighted lever, and kept in continual action by the steam.

Q.Will you describe the mode of starting the engine? A.I may first mention that when the engine is at rest, the connection between the eccentric and the slide valve is broken, by lifting the end of the eccentric rod out of a notch which engages a pin on the valve shaft, and the valve is at such times free to be moved by hand by a bar of iron, applied to a proper part of the valve gear for that purpose.

A.They are usually taken out through a door in the top of the hot well provided for that purpose, which door should be as large as the plates themselves; and it is a good precaution to cast upon this doorwhich will be of cast ironsix or eight stout projecting feet which will press upon the top of the outlet or delivery valve plate when the door is screwed down.

Q.And what is meant by the lap of the valve? A.It is an elongation of the valve face to a certain extent over the port, whereby the port is closed sooner than would otherwise be the case.

The motion given to the valves is rocking, but it will be observed that the valves are not firmly connected to the rocking shaft or cylinder; in the figure the valves are shown shade lined, and the shaft or stem plain; in this way the valves are not affected by the packing of the valve stem, but always rest upon the face of the ports.

Above the upper steam valve V, is a compartment communicating with the steam pipe

When the piston reaches the end of the stroke, the valve has to be moved in the reverse direction, when the piston will return, and after being moved thus by hand, once or twice, the connection of the valve with the eccentric is to be restored by allowing the notch on the end of the eccentric rod to engage the pin on the valve lever, when the valve will be thereafter moved by the engine in the proper manner.

His hands shook, but he gave the pump a few strokes and turned the valve wheel.

Q.Will you explain in detail the construction of the valve gearing, or such parts of it as are peculiar to the oscillating engine?

The valve spindle was hollow, and a prolongation of the screw passed up through it, and was armed on the top with a small wheel, by means of which the plates might be adjusted while the engine was at work.

In our coloured pictures you see many different kinds of shells, some of them built by uni-valve molluscs and some by bi-valve molluscs.

By the valve E a communication may be open or closed between the top of the cylinder and the condenser, so that the steam in the top compartment of the cylinder may either be permitted to escape into the condenser, or may be confined to the cylinder.

If the engine has been run for any length of time, you will always find the trouble in one of these places, but if it is a new one the governor valve might fit a little tight in the valve chamber and you may have to take it out and use a little emery paper to take off the rough projections on the valve.

In consequence of the rotary motion of the balloon, which had continued without ceasing since the earth was left, the valve line had become twisted, and he had to leave the car, and to mount into the ring above to adjust it.

If the valve were without lead or lap the eccentric would be exactly one fourth of a circle in advance of the crank or behind the crank, according to the nature of the valve connection; but as the valve would thus cover the port by the amount of the lap and lead, the eccentric must be set forward so as to open the port to the extent of the lap and lead, and this is effected by the plan just described.

Locomotive valve setting.

The guard should be large, else the disc may stretch in the central hole until it comes over it; but the guard should not permit too much lift of the valve, else a good deal of the water and air will return into the pump at the return stroke before the valve shuts.

The shell C' revolves inside of two yokes (y) and (y'), one attached to each steam-valve toe, (a) and (a') respectively.

Oscillating engine, advantages of, futility of objections to; details of cylinder; framing; condenser; air pump; trunnions; valve and valve casing; piston; piston rod; air pump connecting rod and cross head; air pump rod; eccentric and eccentric rod; valve gear; valve sector; shaft plummer blocks; trunnion plummer blocks; feathering paddle wheels; packing of trunnions.

If, however, the steam continues to escape, the valve sticks in the chamber.