Now you will observe from the model that the action of the governing mechanism is automatic.  As the velocity of the wind increases, the pressure on the side vane tends to carry the wind wheel around edgewise to the wind and parallel to the rudder vane, thereby changing the angle and reducing the area exposed to the wind; at the same time the lever, with adjustable weight attached, swings from a vertical toward a horizontal position, the resistance increasing as it moves toward the latter position.  This acts as a counterbalance of varying resistance against the pressure of the wind on the side vane, and holds the mill at an angle to the plane of the wind, insuring thereby the number of revolutions per minute required, according to the position to which the governing mechanism has been set or adjusted.

If the velocity of the wind is such that the pressure on the side vane overcomes the resistance of the counter weight, then the side vane is carried around parallel with the rudder vane, presenting only the edge of the wind wheel or ends of the fans to the wind, when the mill stops running.

This type of mill presents more effective wind receiving or working surface when in the wind, and less surface exposed to storms when out of the wind, than any other type of mill.  It is at all times under the control of an operator on the ground.

A 22-foot Eclipse mill presents 352 square feet of wind receiving and working surface in the wind, and only 91/2 square feet of wind resisting surface when out of the wind.

Solid-wheel mills are superseding all others in this country, and are being exported largely to all parts of the world, in sizes from 10 to 30 feet in diameter.  Many of these mills have withstood storms without injury, where substantial buildings in the immediate vicinity have been badly damaged.  I will refer to some results accomplished with pumping mills: 

In the spring of 1881 there was erected for Arkansas City, Kansas, a 14-foot diameter pumping wind mill; a 32,000-gallon water tank, resting on a stone substructure 15 feet high, the ground on which it stands being 4 feet higher than the main street of the town.  One thousand four hundred feet of 4-inch wood pipe was used for mains, with 1,200 feet of 11/2-inch wrought iron pipe.  Three 3-inch fire hydrants were placed on the main street.  The wind mill was located 1,100 feet from the tank, and forced the water this distance, elevating it 50 feet.  We estimate that this mill is pumping from 18,000 to 20,000 gallons of water every twenty-four hours.  We learned that these works have saved two buildings from burning, and that the water is being used for sprinkling the streets, and being furnished to consumers at the following rates per annum:  Private houses, $5; stores, $5; hotels, $10; livery stables, $15.  At these very low rates, the city has an income of $300 per annum.  The approximate cost of the works was $2,000.  This gives 15 per cent. interest on the investment, not deducting anything for repairs or maintenance, which has not cost $5 per annum so far.