Long live traditional units

Units that have served us so long and so well should not be allowed to fall into disuse

Holly Else’s article on the development of the Bloodhound supersonic car (December Professional Engineering) was most interesting, and all professional engineers will surely join in wishing the team every success. Particularly refreshing was the use of imperial units throughout her article, and not merely on the grounds of intelligibility. It is important that these units that have served us so long and so well should not be allowed to fall into disuse, otherwise a generation of engineers will be bred to whom they are unfamiliar. They will then have difficulty comprehending any texts written earlier than about the mid-twentieth century, and will be confused if they should have any professional dealing with the United States, the leading engineering nation in the world.

Apart from that we still drive our cars while keeping an eye on the miles per hour, watching out for speed limits signs also in miles per hour. Those of us who calculate our fuel consumption usually tend to do so in statute miles per imperial gallon. Just imagine the confusion if SI were mandatory and new cars suddenly had to have speedometers calibrated in metres/second, and revolution counters had to be in rad./second. So far as is known the western world still flies at speeds measured in knots, the better to navigate in nautical miles, and at altitudes in thousands of feet or flight levels in hundreds of feet. Then at the end of the journey we can enjoy our refreshment in pints! Long live our traditional units, and long may they appear in Professional Engineering.

Gordon Latham, Worthing, West Sussex

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