a large lever in the aviator's right hand. By pulling in on this lever, the rudder was tilted up and the machine was caused to

By pushing out on the lever, the rudder was dipped down. and the machine was caused to descend. This method of control is almost instinctive and very easy to acquire. On the more recent types this front rudder is reduced in size and in addition the rear flap of the upper keel at the stern is moved jointly with it.

GRAHAME-WHITE ON HIS FARMAN AT BELMONT PARK

The rudders and ailerons are all in their normal positions. The bulletin board indicates that he has just completed 19 laps in an hourly distance event. Note the hangars and tents in the distance.

The Direction Rudder.-Two equal vertically placed surfaces in the extreme rear serve as the direction rudder. They are moved jointly and have an area of approximately 30 square feet. A foot lever, hinged at its center, is so connected to these rudders by cables that when the aviator pressing on this lever with his feet turns it, for example, to the left, then the machine will turn to the left.

Transverse Control.-The control of the lateral equilibrium i. e., the tipping from side to side, is effected by the use of "wing

tips," four flaps constituting the rear ends of each plane. A lever in the aviator's right hand (the same one as used to operate the elevation rudder) can be moved from side to side. It is connected. by wires to the lower flap on either side. These flaps in turn transmit the movement imparted to them by the lever to the flaps

directly above them by means of a further wire connection. When the machine is standing still the flaps merely hang down loosely and the wires relax. But as soon as the machine takes to flight the flaps fly out, very much like a flag blown by the breeze, and in this position the connecting wires are extended their full length, and the lever is in control.

If, for example, the machine should tip suddenly down on the aviator's right side then the lever is promptly moved over to the left. This action causes the flaps on the right end of the machine to be pulled down, and since this involves an increased angle

6.2

FRONT ELEVATION OF THE FARMAN BIPLANE

of incidence of the flaps, the lift they exert is increased. This is sufficient to bring the machine back to an even keel. During this process the wires leading to the flaps on the other end have been relaxed, since both sets of connecting wires are taut only when the lever is in mid-position. The flaps on the opposite end, therefore, have in no way been affected, except to be able to fly out more freely in the wind stream.

When making turns, in addition to using the direction rudder, the machine is often artificially inclined by the use of the transverse control. When turning to the right, for example, an instant before setting the direction rudder the lever is moved over to the right side. This lifts up the left end of the machine and therefore causes the turn to be sharper.

Keels. Two horizontal surfaces at the rear, of approximately 80 square feet area, act as keels. Their angle of incidence is low,

and the lift they exert is small, their only function being to steady the machine longitudinally.

Propulsion.-A 50 horse-power 7-cylinder, Gaome rotary, aircooled motor is mounted on a shaft in the rear of the lower plane. A two-bladed Chauviere wooden propeller is directly connecte:l to this motor and rotates with it at 1,200 r.p.m. The pitch of the propeller is 4.62 feet and its diameter is 8.5 feet.

HENRI FARMAN WITH 2 PASSENGERS

Note the control levers and wires leading to the rudders and allerons.