On 2016-04-20 09:06 AM, phiscock@ee.ryerson.ca wrote:
… a remarkably strong case can be made for the weird units of measurements used in the past - rods and chains, for example.
Yeah, spent a bit too much time around plans and surveys. The basis of most land measurement is Gunter's Chain <https://en.wikipedia.org/wiki/Gunter's_chain>, a 17th century invention that made it easy to measure out distances and acreages. One chain is 66 feet, and there are 4 rods (or poles, or pikes) to the chain. There are 100 links to the chain, so it's vaguely base-10 too. The original reason for the 16th and 17th century English mania for survey was the valuation of lands seized from the Catholic church by Henry VIII. It also helped with land valuation for Enclosure, and the end of the Commons. Many land surveys are done in metes and bounds, which are a series of vector measurements from a point (usually a defined survey point; if you ever stumble over a low square metal peg half-buried, it's likely a survey marker) to define a land area. Annoyingly, in the US, most of these measurements use US Survey Feet, which very slightly different to the 12 × 25.4 mm feet that we might know. Tiny aside: My wife's great-great-grandfather surveyed the Santa Fe trail for the carters, who felt that the US government was underpaying them for the distance. Somewhere in the family vaults is the chain that Martin O. Jones and his team dragged from Independence, MO to Santa Fe, and proved the carters right. units(1) has many interesting asides on measurements. cheers, Stewart