Introduced by Michael Knowles, Member, on 17 May 1999

Compared with the proverbial man in the street, BRLSI members include a high proportion with above-average familiarity with or awareness of the Metric System. From medicine, through carbon-dating in archaeology, via nuclear physics to ISO metric standards for technology, many of us employ metric units without either cultural problems or sparing a thought for the alternatives.

The speaker was an undergraduate at the University of Manchester when the President of the Board of Trade, then the Rt Hon Douglas Jay MP, sent a Parliamentary Written Answer to John Horner, Labour MP for Oldbury and Halesowen, on 24th May 1965, that the Metric System would "become our primary system of weights and measures within ten years".

In 1970, the Metrication Board reported to the Minister of Technology, the Rt Hon Anthony Wedgwood Benn MP, that Britain would be a metric country before 1975.

Britain did indeed decimalise her currency and metricate the UK pharmaceutical industry in 1971. However, in other everyday fields the subject was so mismanaged, or probably `unmanaged' is a more accurate term, that there still seem to be millions of citizens who are blissfully ignorant of metric units _ unaware that for most practical purposes, nine litres equal two gallons, and that 28 miles per gallon is equivalent to 10 litres per hundred kilometres. The last time that help with metrication was given to the general public by government was twenty years ago, in the form of brochures including one on how to make a metric cake! These introduced the European shopping pound of 500 grams to Britain, but that and the Metrication Board itself were abolished by Thatcher. Local supermarkets are now pedantically showing metric equivalents of the old Imperial weights and marketing frozen peas in bags of 907 grams (2 1b avoirdupois)!

The speaker made a commemorative visit to the Academy of Sciences in Paris on 22nd June 1999, the exact anniversary of the day when the original standards were presented in 1799. Lest it be forgotten by us islanders, there were forty years of strife and confusion in France before the Metric System was made obligatory in its homeland.

The Metric System is still perceived by many in Britain as a purely French thing but it is actually used by 150 nations and was presented at its inception "for all peoples for all time".

The metre is the fundamental unit of length and is based on latitude. Ten degrees of latitude intersect with the Paris meridian before it meets the coast at Dunkirk in the north and Barcelona in the south. This distance was measured by the intrepid French astronomers MM. Delambre and Mechain, from 1792 to 1798. The actual distance measured was 551,584 toises (i.e.old French fathoms of 1.949 m) and this became 1,075 kilometres, of which there are by definition ten thousand in ninety degrees of the global quadrant from the Equator to the North Pole along the Paris meridian. The task of its measurement was truly an odyssey through turbulent revolutionary France, and a book about the adventure has been written by a lecturer from Paris University VIII, Dr Denis Guedj. The latest edition, with interesting new appendices, is entitled Le mètre, la mesure du monde and is available via The French Bookshop Ltd at South Kensington, near the French Institute.

The other vital dimension in the Metric System is time, which man historically measured against the apparent revolution of the Sun around the Earth. This was justification for a visit to the Paris Observatory to witness a solar transit. It might be more than mere coincidence that the original standards were presented on the day after the summer solstice, and a photograph of the transit is reproduced below.


Solar Transit
This was actually a contingency shot taken two days previously, for it was cloudy on the day. A commemorative certificate was transmitted to the BRLSI by facsimile at the moment of transit. Paris solar time is officially 9 minutes 21 seconds in advance of Greenwich, corresponding to a longitude of 2° 20' 15" East. Other items of interest at the Observatory include a solar exhibition, a permanent display of historic astronomical instruments, and the original speaking clock, of which Paris had the first example in the world. It was inaugurated on 14th February 1933. In the early nineteen-sixties, it made an erroneous announcement, so new machines were designed. In 1991 these were replaced by three new units with alternating male and female voices.

The Paris Observatory is a wonderful time-capsule, set in peaceful gardens behind a high wall in the 14th Arondissement, about 500 metres from the Metro station Denfert-Rochereau. The building above it bears an enamelled plaque stating "Ville de Paris - Unification de 1'Heure", and the city still possesses a network of historic slave clocks set unobtrusively in walls around the city. The observatory was built between 1667 and 1672 and so (on public open days) one enters fine wood-panelled rooms, which have served their original purpose for well over three centuries. The only significant changes have been the addition of electricity and a new library wing. It is an intellectual stimulus to scan rows of books in the French language, to which the ordinary UK citizen has no access whatever, but it is worth mentioning one title in English, which can be obtained via interlibrary loan: Cartography in France by Josef W. Konvitz; Chicago; 1995.

Michael Knowles