Stephen Davis wrote in USMA 15062: >I am myself (as many on the UKMA list will testify) in no way, shape or form >a maths whizz, John, yet, what system would you consider to be the easiest >to use?? >Which are the more accurate scales?? The ones calibrated in ounces only?? >(1oz = 0.0625lb or 1/16lb) Or the ones that are calibrated in grams?? (1g = >0.007oz or 1/14oz)?? > >Which one of these is infinitely more accurate and simpler to use?? > >I know which one of the two I would pick!! Stephen has hit the nail on the head when he said that SI is easier to use, but he is wrong when he states that SI is more accurate than inch-poind. Accuracy is how close a measured or stated value is to the true value. Precision is the measure of the tolerance implied by a measurement. Both the accuracy and precision of measurement by an inch-pound instrument can equal that of an SI instrument. However, the answer provided by the inch-pound instrument is much harder to do arithmetic with. I have a vernier caliper with two scales: one reads to 1/128 inch and the other to 0.1 mm. I find the inch scale incredably difficult to read, even though its implied precision is about half that of the millimetre scale. It is interesting that traditional craftsmen measure inches to 1/16". For more precision that they go to thousandths of an inch. Joseph B. Reid 17 Glebe Road West Toronto M5P 1C8 Tel. 416 486-6071
