My thanks to Pat Naughtin for pointing out an errorin my USMA 21374 in the numbering of the paragraphs in the South African document on the centimetre. The paragraph that I numbered 9 was in fact paragraph 8.
Paragrph 9, which I did not quote, was; 9. One of the objections raised against the millimetre is that it is said to be difficult to visualize a dimension such as 250 mm. Yet nobody has any difficulty in thinking of 250 mL as a quarter of a litre and 250 g as a quarter of a kilogram. Perhaps the answer lies in the fact that we automatically relate 250 mL to the litre, the 250 g to the kilogram, yet when it comes 250 mm, we try to visualize 250 tiny divisions on a ruler instead of relating it to the metre. It is suggested that once one cultivates this habit of relating millimetre dimensions to the SI unit, the metre, much of the "antipathy" towards the millimetre will disappear. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 Tel. 416 486-6071
