of the cut-off valve, G. F represents the stem of the main valve, and B the stem of the cut-off valve, which is continued on through the end of the steam-chest, and is held steady when the engine is working by means of a horn at A. The reader will notice that there is a rack cut in the back of the cut-off, which engages the teeth of a small wheel on the valve-stem, and from this device any one would soon come to the conclusion that the adjustment of the cut-off is accomplished by rolling the valve-stem. This, as a matter of course, will raise and lower the cut-off valve by means of the rack and pinion, thereby opening the ports.

The governor, which is very powerful and sensitive, embodies some peculiarities of design and construction not common in governors, inasmuch as the point of suspension, instead of being on the same side of the spindle as the ball, is carried over to the opposite side, thereby greatly increasing its power and sensitiveness. Directly under the governor there is a disc on the valve-stem, with teeth cut on the periphery about half the circumference, and these teeth engage a rack connected with the governor-spindle. Consequently, as the balls of the governor rise and fall, a proportional movement will be transmitted to the cut-off valve. To determine the point at which the engine is cutting off when running, the plain part of the disc, which is connected with the governor and valve-stem, has marks and figures upon it, each mark indicating a point in the length of the stroke. There is a point which coincides with these marks, and can be seen under the pulley attached to the governor. To increase or diminish the speed, a counterweight is attached to the end of the governor-spindle, under the steam-chest.

These engines possess many excellent features. The bearings are well proportioned and all the parts thoroughly fitted; the fly-wheels are turned on the face and sides and accurately balanced; the connecting-rod and crank-shafts are made of the best hammered wrought-iron; the crank- and wrist-pins are made of steel; the connecting-rod boxes of gun-metal, and the main-bearings lined with the best anti-friction metal; while the cylinder is cast of car-wheel iron, and jacketed to prevent radiation.

Steam-Engine Governors.

The subject of regulating the speed of steam-engines, and more especially those which, from circumstances and the nature of the work to be performed, are liable to constant change, has of late years received no little attention from engineers and practical inventors, and as a result various kinds of governors have been introduced. It would be safe to say that this device has absorbed more thought, and received more attention on the part of mechanics, than any other adjunct of the steam-engine. In the ordinary governor, the principal part of the apparatus consists of a pair of balls revolving round a vertical axis or spindle driven by a train of mechanism, generally mitre-gears, which causes their angular velocity of revolution to bear a fixed ratio to the velocity of the prime mover. The rods of the pendulums place themselves at an angle with the vertical

The Waters Governor.

axis, so that the common height of the pendulums is that corresponding to the number of turns in a second. The regulator must be so adjusted as to be in the proper position for supplying the proper amount of power when the pendulum-rods are at the angle of inclination corresponding to the proper speed of the machine.

When the speed deviates above or below that amount, the outward or inward motion of the pendulum-rods acts on the spindle, so as to open the valve when the speed is too low, and close it when it is too high.

In the attainment of this object, the principle of centrifugal force, as embodied in the old fly-ball governor of Watt, has been more resorted to than any other; but, aside from this, the governor has been so improved, altered, and reconstructed, since his time, as to be almost unrecognizable; but still the old principle is there, and also the three prominent defects which so materially interfere with its efficiency. The first of these is friction which arises from the joints, and is caused by swinging the balls or weights by the short end of the arm or lever to which they are attached. The second defect is due to the fact that the balls, as they assume different positions in keeping with the speed with which they revolve, are obliged to rise or fall. This is necessary in order that the resistance which the weights offer to centrifugal force should constantly increase; if it did not so increase, the weights, when once started from their position of rest, would instantly go to the extreme limit of motion. The rising of the balls shortens the distance which they are allowed to move for a given variation by bringing the centres of ball and arm on which they swing into a straight line, so that a variation which moves the balls a given distance upward, if it occurs again, will not move them nearly so far in the same direction. Again, the same force that would support the balls in any plane would not raise them to that plane from a lower one. So between friction, which destroys the delicate power that the balls assume under a slight change, and the necessity for a large change to overcome their inertia, it is almost impossible to attain a degree of regulation which would be equal to all requirements.

Governors when attached to throttle-valves work under circumstances that necessitate the use of openings for the passage of the steam that are too small in area, so much so that the useful effects of the steam are considerably diminished. On this depends

the ill repute of throttling engines as compared with those which regulate by governor controlled valve motions or variable cut-off. If the valve of a governor has too large openings, it will, owing to the unsteady action of the governor, admit too large a quantity of steam, and cause a jumping of the engine; then, in trying to shut off this extra amount, it shuts it all off; in fact, the governor cannot fix it exactly right, being incapable of delicate changes. This difficulty is best met by making the openings in the valve of peculiar shape, so that they open and close in a ratio different from that of the governor. With a governor that would run perfectly up to theory, and be steady and capable of taking a posi tion in keeping with the speed, and not leaving it without a change in speed, a very large area might be used, and the do useful effects of the steam would not be impaired, neither would there exist a necessity for great changes in speed to get the required opening and closing of the valve. The extra amount of steam required to drive a heavy addition of load on an engine is surprisingly small, provided that the engine can get the steam at the very instant the load is applied, and before the momentum of the machinery becomes much reduced; but let the engine once get below speed, the circumstances will be very different, as, even without any load, the engine would take some time to come to speed. The third defect in governors on throttling engines is that the spindle or valve-stem has of necessity to pass through steam-tight,

The Shive Governor.