THE problem which the bomber on board an aeroplane has to solve is more difficult than the corresponding problem of the bomber on board an airship, since the aeroplane must move with respect to the air to support itself, while the airship may be brought to rest over the object to be bombed. The bomb on release has a horizontal speed equal to that of the aeroplane, and if the air were at rest and offered no resistance to the motion of the bomb through it, the path of the bomb would he a parabola with its axis vertical and its vertex at the point of release. The resistance of the air prolongs the time of fall of the bomb to an extent which depends on its size and weight, and may be 50 per cent. if the overall density of the bomb is small. Any horizontal motion of the air causes a drift of the bomb down the wind which depends on the speeds of the various layers of air through which it passes during its fall, and on the resistance the air offers to the sideways motion of the bomb through it.