Imperial measurements - how were they devised?

[kerryb]

Hi

Something has been bugging me since Sunday?  My 7 year old niece has been learning about decimal measures at school and she asked me why they are always in sets of 10 when the old measurements were in 12s.

I told her this was strictly true but she wanted to know, and I wasn't able to tell her why we have 12 months in the year and 12 inches in a foot etc. She asked me how many feet in a yard and my sister and I were flummoxed, we think it is 9 but can't remember having learnt decimals ourselves at school.

Can anyone tell me where the old Imperial measures came from?

Kerry

[Dave Francis]

Hi Kerry

I can't tell you exactly why there are 12 inches in a foot (we are talking about a system of measurement that's deeply entrenched in history and custom) but I can tell you that there are three feet in a yard. 

There's some interesting info about historical weights and measures here:

http://users.aol.com/jackproot/met/spvolas.html

There's plenty of other stuff on the internet of course.

Dave

PS: A tradesman (of the old school) will always tell you that it is easier and more accurate to work in quarters, eighths, and sixteenths of an inch since these are all exact multiples of each other.

[kerryb]

That's an interesting link Dave, thanks 

Whoops got that wrong, but at least 9 is a multiple of 3 

Kerry

[trish251]

As I remember it, chains relate to the actual size of 100 links in a chain that was used by surveyors to measure the land they surveyed. (not difficult to know I have some surveyor ancestors  ) why 1 chain became the length of a cricket pitch I know not.

This link also gives some  derivations of the measurements
http://gwydir.demon.co.uk/jo/units/length.htm

Trish

[bearkat]

There are interesting articles about the origins of length measurements on these websites:

http://www.npl.co.uk/about/history_length/page04.html

http://www.unc.edu/~rowlett/units/custom.html

Although they don't seem to agree.

[trish251]

There are interesting articles about the origins of length measurements on these websites:

http://www.npl.co.uk/about/history_length/page04.html

http://www.unc.edu/~rowlett/units/custom.html

Although they don't seem to agree.

I just hate getting 2 reasons for the same event - then you just have to spend forever trying to work out which is correct. I'll just browse one of your links (speaking of imperial measures)   

Trish

[Shropshire Lass]

You have to go much further back to find someone to "blame"

The Sumerian society, 4000 years ago, used a type of base sixty number system.  The number sixty can be divided by twelve factors and is the smallest number that can be divided by every number from 1 to 6.  This makes it very functional because fractions are so simple using it.

We still use the system for time - one hour = 60 minutes, one minute = 60 seconds - and for measuring angles - 360 degrees in a circle, 60 minutes in a degree, 60 seconds in a minute.  Counting in twelves is a hangover from this base 60 - twelve months in a year, selling goods in dozens, etc.

The system has been adapted and incorporated into later counting systems adding to the confusion of the imperial system. 

(I don't know a lot about maths but I am interested in the early human cultures.)

Monica

[Little Nell]

The months in the year is to do with the cycles of the moon - so you can blame that on nature, the big bang, creation or whatever.  The earth-bound (but maybe aspiring gods) then came along and fiddled with it according to their own personal agenda.  It's only as observations got better and the observers cleverer as working things out that we came up with what we have now.

Nell

[GeoffE]

The months in the year is to do with the cycles of the moon -

But we get 13 moons per year.