I believe that it is now generally known that Britain is “going metric”. It does not seem to be as well known that we will, in fact, be adopting the Systeme International d’Unités.
In particular it is rumoured that the Ministry of Transport is intending to introduce speed limit signs in kilometres per hour in 1973. It should be noted that the km./hr. is no more a SI unit than is the m.p.h.—the correct SI unit is the metre per second and, in the interests of consistency of scientific and practical units alone, this should be the unit of velocity to be adopted.
But there would be an additional bonus in terms of road safety if metres per second were used. At the moment a driver glances at his speedometer and thinks “60 m.p.h.! I’ll be home in half an hour”, which, however briefly, takes his mind away from his present situation. The SI unit keeps him firmly in nearby space and time—”25 metres/ sec.! I’ll be at that pedestrian crossing in another second”.
These considerations will not matter much to the experienced driver who has developed an intuitive feeling for space and time in relation to the performance of his vehicle, but to the inexperienced, who is most prone to accident, the difference could be, literally, a matter of life and death.
I would urge scientists, particularly teachers of science and of mathematics, concerned with the uniform adoption and application of SI and all people concerned about road safety to bring your views to the notice of the relevant authorities quickly, in the hope of preventing a costly mistake.
JOHN BALDWIN, B.SC. – Accrington