The present-day tendency of automobile design is to increase the power/weight ratio of the engine, while at the same time retaining or improving the efficiency, and to reduce the weight of the chassis generally for a given power. The drawing office creates the efficient engine, and the inspection department enables the design to be put into and maintained in effective production. Now, the modern high-efficiency machine is due, amongst other things, to a more accurate knowledge of stress distribution, and consequently the factor of safety, or the factor of ignorance as it sometimes used to be named, may approach unity—provided that the materials used are consistent.