The general name "airscrew" will be used throughout for the organ of propulsion of aircraft.

When the airscrew is in front of the main lifting surfaces it is called a tractor, when behind them a propeller.

When it turns clockwise, as seen by an observer standing in the blast (i.e., behind the aircraft) it is called right-handed and, when anti-clockwise, left-handed. Airscrews are thus classified as :— Propellers or Tractors. Right-handed or Left-handed.

That vertical currents or components of air-motion having a velocity of several meters per second occasionally occur in the lowest tow kilometers of the atmosphere is an observed fact, but we are far as yet from compleate knowledge as to the conditions which produces such motion

I suggest, however, that wave-motion proper, that is low-velocity, periodic oscillations of pressure or temperaturem whether transmitted from a distant source of disturbance, or occurring under the continuous interaction of two horizontal currents of air can be ruled from any list of hypothetical causes of important vertical motion.

The following table is the result of a series of tests carried out at East London College (University of London) on various methods of mounting flexible steel cables, in cable ends.

The specimens were kindly supplied by Messrs. T. W. K. Clarke and Co.

Cables Nos. 1 and 3 were fixed in the following manner. The ends were knotted and tinned, then inserted in sockets or cable ends, and solder run in.