Fouling

The threats range from diesel exhaust and unchecked forest fires fouling the air to untreated waste poisoning the water.

A new type of fouling point indicator is being tried out by the London Transport Executive. Until now the standard method of indicating the point nearest to a junction of two stabling roads where a train can stand without fouling the adjacent road has been by fixing the letters "FP" [fouling point] to the sleepers of the road concerned.

Probably, rifling evolved from the early observation of the feathers on an arrow-and from the practical results of cutting channels in a musket, originally to reduce fouling, then because it was found to improve accuracy of the shot.