The rising or falling of the balls of this governor to only a very slight extent will bring into action a power that is driven by the turbine itself, which is able to move the water-gate in either direction according as the balls rise or fall. For instance, if the balls rise beyond their normal position, it shows that the dynamo is increasing in speed, and immediately machinery is brought into action that shuts the water off in a small degree, just enough to bring the speed back to normal. If the balls drop to any extent, it shows that the load is too great for the amount of water, and that the dynamo is decreasing in speed; immediately the power is brought into action, now in the opposite direction, and the water-gate is opened wider. These slight variations of speed are constantly going on, and the constant opening and closing of the gate follows with them. It is a beautiful piece of machinery, and is beautifully adapted to the work it has to perform. It is continually standing guard over this greater piece of machinery that is exerting an energy of 5000 horse-power and prevents it from going wrong, both in doing "that which it should not do and leaving undone that which it should do." It is a machine that, when in action, points a moral to every thinking person who beholds it. Every man has such a governor if he only has the inclination to use it. I have said further back that the water-head varies, but usually at long periods. This variation is chiefly caused by changes of wind, and it is very much greater than one would suppose without studying the causes. Lake Erie lies in an easterly and westerly direction, and when the wind blows constantly for a time from the west, with considerable force, the water piles up at the eastern end of the lake, which causes the level of the Niagara River to rise to a very sensible extent. It is not so noticeable above the falls as below, because of the great difference in the width of the river at these two points. Sometimes the river below the falls, as it flows through the narrow gorge, will vary in height from twenty to forty feet. When the wind stops blowing from the west and suddenly changes and blows from the east, it carries the water of the lake away from the east toward the west end, which will produce a corresponding depression in the Niagara River. No doubt there is an effect produced by the difference of annual rainfall, but the effect from this cause is not so marked as that from the changing winds.