What are the positives and negatives of the old English customary system of measurements?

Answer 1

Positives: Almost none. There are some people who are not familiar with the SI system but they are a tiny minority. In any case, that is hardly a good enough reason to continue using a system that has few other redeeming features.

Negatives:

1. Only a few recalcitrant countries still officially use it: US, Burma and Liberia are the larger ones. Even in the US, scientists normally use SI. When they don't they have disasters like the one that trashed NASA's Mars Climate Orbiter!

2. It is not based on internationally agreed units. For example the gallon can mean one amount in the US and another in the UK.

3. Orders of magnitude for the same measure are related by a horrendously complicated system of conversion factors. For example,

• 2 pints in a quart
• 3 feet in a yard
• 4 quarts in a gallon
• 6 feet in a fathom
• 8 furlongs in a mile
• 9 square feet in a square yard
• 12 inches in a foot
• 14 pounds in a stone
• 16 ounces in a pound

and so on, and on and on. By way of contrast, the SI uses simple decimal conversions and only a handful of prefices are required (although there are a lot more). The decimal structure also makes it simple to use scientific notation for very small and very large quantities.

4. There are few simple relations between measures for one characteristic to another. In the SI, for example, the unit of length is 1 metre. 100 square metres = 1 are, the unit for area. 1 cubic metre = 1000 litres, which is a multiple of the unit for volume. No complicated conversions to learn.

5. The decision really is a no-brainer.