Dear Carl, The hectare is widely used in Australia as an area measure for farming land. It has an area of 10�000�square metres (m^2) so it is convenient to use for rainfall and irrigation calculations. For example, since 1 millimetre of rain is equivalent to 1 litre of water on 1 m^2, it follows that 1 mm of rain on a hectare is equivalent to 10�000 litres of water or 10 kilolitres.
I generally think of a hectare as a square with 100�metre sides but I know that a hectare can have many other shapes. Back in the olden days � when we did conversions from old units � I used to think of an acre as about 4000�m^2. This meant that there were about 2.5 acres to 1 hectare; you might like to compare that with the conversion value on your calculator. During the sub-urbanisation of Australian cities, in the 1940s and 1950s, the idea of a 'quarter-acre block' was popular for building suburban houses. Now it is convenient to think of these as '1000 square metre blocks'. Cheers, Pat Naughtin CAMS Geelong, Australia on 2002-08-22 04.19, Carl Sorenson at [EMAIL PROTECTED] wrote: > David Owen wrote: >> The metric system would catch on faster if its evangelists were more >> sensitive to other traditions, and less unbending about deviations >> from theoretical consistency. > > I couldn't have said it better myself. I think all USMA members should > engrave this on a plaque and post it in a place they will see often. > > My XML page has moved to http://ssp-web.lib.byu.edu/measurement/ and it > now includes an option to specify significant figures. I can't > guarantee that the site will always be up. > > I have a question about the hectare. According to NIST at > http://physics.nist.gov/cuu/Units/outside.html, the hectare is one of > the "units outside the SI that are currently accepted for use with the > SI, subject to further review" whose "continued use is not encouraged." > The hectare seems to me to be a very useful unit. It seems more > practical for some purposes than square kilometers and square meters for > the same reason that the liter is more practical than cubic meters and > cubic millimeters. > > I presume that a hectare is 100 "ares" and an "are" is 100 square > meters. Is this correct? How is this unit pronounced? I have a > calculator with a conversion chart that refers to "acre" rather than > "are". Is this a typo? > > Carl >
