19 SEPTEMBER 1970, Page 25

Metrication mania

Sir: At a time when we are being bulldozed into accepting the metric system there are some facts which should be considered. First, the units of the metric system are not all good compared with the majority of weights and measures that have been used through- out the ages because, being arbitrarily based, they are of inconvenient size for most pur- poses. Second, the system, having been de- vised prior to the age of scientific discovery, is not fitted to calculations involving those values, such as the force of gravity, joules equivalent, etc, that are so frequently re- quired in engineering calculations. Third, the particular form of metric system that is being proposed is stultified by the purpose- less rejection of some of the most useful units—e.g. the centimetre, the decimetre, the square centimetre, the minute and the hour —leaving some which are very unsuitable for many everyday purposes.

For example it has been suggested that flows of water and sewage should be measured in cubic metres per second: this would have the result that the vast majority of water and sewage calculations would be in terms of small decimal fractions. The sug- gestion that the capacities of reservoirs should be measured in litres is in the same order of absurdity as to suggest that the distance between the earth and the moon should be measured in inches!

An ideal system of measurement for scientific purposes is one in which the stan- dard force of gravity is unity, the heat re- quired to raise by one degree of temperature a body of water occtrtwing a cube having a side measurement of one unit of length should be (about) equal to one thermal unit and this should equal the amount of energy required to lift that mass one unit of length against standard gravity.

It is, however, necessary for units of time. length, volume and mass to be convenient and acceptable. and this means that some compromise may be desirable. For example, the force of gravity could be ten instead of unity and mechanical and/or thermal energy

could be related to electrical energy by some simple factor such as four or a power of ten.

It is not difficult to devise such systems of measurement, and quite a few would appear to be acceptable. Moreover, it is interesting to observe how often ancient units, such as the Phoenician talent, re-emerge when such systems are worked out.

In view of the foregoing, it should not be considered unlikely that, in the not too distant future, some committee will be sug- gesting the adoption of a new system of measurement much more suitable to the re- quirements of commerce and science than any at present in use. And then we might be asked to change all over again.