The generation gap

In his recent article “Why I …”,  Ronnie Cohen looked at the present to explain why he believes the UK should complete the transition to metric units. However, some of those who commented on his article also looked back. In this article, I take another look into the past and then ask if the fading of such memories might prolong the measurement muddle.

At my primary school in the early 1950s, we celebrated Empire Day (in late May), and we were taught imperial, not metric, measures. The backs of the school-issue exercise books were printed with tables of imperial measures which served only to confuse – pecks and bushels, chains and cables, fathoms and furlongs, pounds (avoirdupois), ounces (troy) and ounces (fluid), miles (statute) and miles (nautical), and on, and on. Needless to say, imperial ruled on the sports field: the 100 yard sprint, the 4 x 110 yard relay and the mile come to mind.

The first science lesson in secondary school brought a surprise. The teacher, brandishing a metre rule, told us that there was an alternative system of measures, that scientists used it, and henceforth so would we. Even so, lessons were not entirely free of the measurement muddle. When we started a subject called applied maths in the sixth form, we reverted to imperial. The poundal, a unit which was not in those tables on the back of the exercise books, put in an appearance. New factors had to be learned, like 1 pound force is 32 poundals and 60 mph is 88 ft/sec.

Foreign travel by teenagers was the exception rather than the rule in the late 1950s. So a visit to Denmark in 1959 produced another surprise. This metric system, with which we had become familiar through our science lessons, was in everyday use in homes, in shops, and on the street. And it seemed to work just as well in those situations as the imperial system did in Britain.

University compounded the educational confusion. Some subjects like structural design, fluid mechanics, and thermodynamics were taught in imperial. Stresses and pressures were measured in tons/sq ft, or pounds/sq in or pounds/sq ft depending on the application. New units were encountered, such as slugs, kips and °R. Other subjects were taught in metric, such as electrical technology. Soil mechanics managed to combine laboratory work in metric with theory and design in imperial. And on our field surveying course we came across the engineer’s chain of 100 links (literally), each one foot long, and the surveyor’s chain of 22 yards.

Then on to the world of work – a job on a construction site, and new variations on the imperial theme. The levelling staff was graduated in hundredths of feet, not inches and eighths, to facilitate the subsequent calculations, but measuring tapes were in feet, inches and fractions. Measurements of excavations were made in feet and inches, but volumes were calculated in cubic yards. Arcane tricks, doubtless going back to the Victorians, were used to convert one to the other, as pocket calculators were still unheard of.

Happily (for me at least) this muddle did not last long. In 1969, the construction industry announced it would go metric, following the lead from government. In a single leap, we would switch from imperial to SI, by-passing the metre-kilogram-second system (MKS) and metric technical units. Before long, new measuring scales and design tables were being handed out by the boss (I was in the design office by then), the first metric job arrived, I heaved a sigh of relief, and that was that. An era had ended, or so it seemed.

Today, those who are focused on their particular areas of interest and determined to resist change, including market traders and successive UK ministers of transport, try to persuade us that their inertia has little impact on the wider economy. In response, some like Ronnie point out that completion of the metric conversion in the UK would make all our lives so much easier. Others like me look back. Will our fading of memories of the measurement muddle of forty or more years ago reduce the drive to finish the job? Indeed, is there now a generation gap? And one wonders what future generations, accustomed to a metric world, will make of it all.


It is interesting to note one impact of the metric changeover on the construction industry. As the UK government foresaw in 1965, markets for design in imperial units in countries of the former British Empire shrank steadily during the 1970’s. Equipped with skills in SI, the new worldwide standard system of measurement, British consultants were able to maintain and expand their businesses abroad. Arups became established in China for example, and Norman Foster won the design competition for reconstruction of the Reichstag in Berlin and also assisted with the Millau Viaduct in France. Today, in a strange twist, British consultants find themselves takeover targets of US companies facing declining markets for design in US customary units.

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3 Responses to The generation gap

  1. Richard Ational says:

    My secondary school experience that commenced in the early 1960s closely mirrored that of derekp. His description of further and higher education prompted me to look out some of my old text books that related to the study and training for my registration in electrical engineering. The prefaces to these revealed some interesting insights into the train of thought at the time of their publication :

    Book 1

    First edition, published in 1953

    “Electrical theory has been burdened with several systems of units. In 1901, it was suggested by Prof. Giorgi, an Italian scientist, that the confusion caused by these different systems could be eliminated by the adoption of the metre, the kilogramme and the second as the units of length, mass and time respectively and the adoption of one of the practical units, such as the ampere, as a fourth fundamental unit. This metre-kilogramme-second (M.K.S.) system in its rationalized form was adopted unanimously by the International Electrotechnical Commmission in 1950; and in April, 1952, the Council of the Institution of Electrical Engineers recommended that this system 'should be employed by authors in papers submitted to the Institution and that all students of electrical engineering should become conversant with its use'. The rationalised M.K.S. system has, therefore, been adopted in this volume and, apart from the conversion table given on p. 383, no reference has been made to the C.G.S. electromagnetic and electrostatic systems.

    The symbols and nomenclature are in accordance with the recommendations of the British Standards Institution and the Institution of Electrical Engineers; and for the convenience of students, the symbols and abbreviations used in this book have been tabulated on pp. …”

    Third edition, published 1970

    “In 1960 the General Conference of Weights and Measures recommended that the International System of Units should be universally adopted. This system is an extension and refinement of the traditional metric system. It embodies features which make it logically superior to any other system as well as being more convenient in practice: it is rational, coherent and comprehensive.

    In this revised edition, references to British units have been deleted, but a Conversion Table has been added, giving the relationships between these units and the corresponding SI units. The changes also include the substitution of magnetic field strength and electric field strength for magnetising force and electric force respectively, and the use of the terms hertz, tesla and siemens. The joule is used as the unit of energy, whether mechanical, electrical or thermal, but the kilowatt hour is retained when the latter is the more convenient unit.”

    Book 2

    Fourth Edition, published 1969, third impression 1972

    “The principal changes in this edition are concerned with nomenclature in order that the terms may be in agreement with the International System of Units (SI) adopted by the International Organisation for Standardisation and by the International Electrotechnical Commission. These changes have involved the replacement of mho by siemens, of weber per square metre by tesla, of cycle per second by hertz and of lumen per square foot by the metric unit lux representing lumen per square metre. Also, the unit of magnetomotive force is the ampere rather than the ampere-turn, and that of magnetising force (or magnetic field strength) is therefore the ampere per metre.

    The joule should, in general, be adopted as the unit of energy, whether mechanical, electrical or thermal, but it is permissible to use the kilowatt hour when the latter is the more convenient unit.

    The references to British units have not been deleted since these units will continue to be used-but to a diminishing extent-during the period of change-over to SI units.

    In the 1972 impression, references to British units have been deleted except for a conversion table on page 695. The terms magnetising force and electric force have been replaced by magnetic field strength and electric field strength respectively; and an appendix on the generalised theory of electrical machines has been substituted for the trigonometrical and log tables. Also, for ease of reference, definitions of SI units are listed on page …”.

    So there we are. In 1952 the IEE “recommended that this (metric) system 'should be employed by authors in papers submitted to the Institution and that all students of electrical engineering should become conversant with its use’ ” (note the spelling of kilogram in the original text). By 1972 the change to SI in electrical engineering was complete.

    Why then does the successor to the IEE, the Institution of Engineering and Technology (IET) now publish a periodical “E&T” that contains the usual hotchpotch of units that we in the UK are expected to tolerate ? Is there anybody out there who can provide an excuse on their behalf ?

  2. John Steele says:

    My experience was similar. Grade school was primarily US Customary. I do not recall learning about metric until I took chemistry and physics in high school, ca 1959-1961. I attended MIT and majored in Electrical Engineering. Courses were taught exclusively in "rationalized mksa," immediate precursor to the SI. (I have never used the cgs electrostatic and electromagnetic units, and don't understand them.) This was NOT the policy for science and engineering majors at other colleges, so I feel somewhat lucky. If we encountered a problem in Customary units, we were taught to convert the problem, work the problem in metric, and convert the answer if required; otherwise points were deducted from our solutions. Except for trivial problems, I use that approach to this day. I can not do complex engineering work in Customary. (I do know what a slug is, and the degree Rankine, but until recently I did not know what a poundal is.)

    I remember the introduction of the pascal (vs newton per meter squared) for pressure, siemens to replace the "mho" (reciprocal ohm) and picofarads to replace micromicrofarads.

    Fortunately, my first employer was dual and wanted to go metric; I served on the metrication committee. My second employer was metric. So my inability to engineer in Customary was never a real problem. Since this was very much pre-Internet, it was hard to find simple answers about Customary, like "how big is a gallon." Sources would inter-relate pints, quarts, gallons, etc, but it was VERY hard to find a US gallon was 231 in³.

    As we insisted our supply base be metric to, I never really encountered engineers who worked in Customary, although I was aware they existed. In my final assignment, I was head of technical planning and interfaced with universities, national labs, NASA, etc. I was VERY surprised at both national labs and NASA to find engineers who thought in Customary and only converted to metric because their bosses made them. At first I thought they believed we used Customary. I made clear that we didn't, and we proceeded to have translation difficulties that precluded fruitful discussion. Although he was writing about something quite different, it reminded me of C. P. Snow's "The Two Cultures," two groups who couldn't talk to each other.

    On the other hand, as the US is considerably less metric than the UK, I had to learn enough Customary to "survive" in my personal life. Needing to know two systems can only be a nuisance and waste of time.

  3. BrianAC says:

    Interesting replies, @Richard.
    I too did the electrical (electronic) engineering and it seems I had the second edition (Renton?) published in 1968 to the revised MKS system. I was only on day release in 1959 / 1960 and that was 100 percent metric (I think). I went on to travel the world with my work so got pretty used to swapping between various systems but metric was predominant anyway. My real phobia was with nuts and bolts. Surprising really that no matter how high the technology, it is all held together by nuts and bolts at base level. On a job in the late '70's I guess it was, working for a UK firm in some far flung desert I was mixed up in my first real 'metric muddle'. I had 3/8 inch (or 5/16?) bolts with 8 mm nuts and 1 inch pipe with 25 mm fittings. I had quite a hard time trying to explain that they would not fit together and were in fact different systems, not just metric conversions.
    In later years, metric was the norm but as most equipment was American, it became increasingly difficult to obtain what I then started calling 'American fittings'. As a result my budget spending tried to avoid the American market whenever possible (broad hint to US industry) and switched to Europe and UK. German companies always spoke excellent technical English so no problems there. UK was always a lottery as to what you got, so had to be careful. In recent years though back in UK (retired), I see a slow creep back to the usage of imperial fittings and design, UK manufacturers and/or importers and/or wholesalers and/or retailers are just not getting the message. I now trawl the internet more than ever to buy things that do not display any sign of imperial history or dual labeling, and preferably with dimensions that are not just metric equivalents.
    Those of us that have been through it all just want out. I never want to see an inch pipe or bolt again, nor a mile of road. Dream on!


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