Pat Naughtin in USMA 27361 wrote at length about angle measurement. It
would be useful to consider the present situation.
Wild of Heerbrugge, Switzerland, makes theodolites graduAted in gons,
grads or grades (chose whichcver name you wish).
"The International System of Units" (SI) lists the radian and steradian
as "SI derived units" and the degree, minute and second of angle as
"Non-SI units accepted for use with the International System". A
footnote says "ISO 31 recommends that the degree be subdivided
decimally rather using the minute and second". It does not mention the
gon, grad, or grade.
One-third and two-thirds of a right angle are angles that appear
frequently in mechanical engineering. With 100 gons to the rightangle
these angles are expressed as 33.333... and 66.666..., while in degrees
they are 30 and 60. Degrees are universally used in mechanical
engineering, cartography, and astronomy. The International System (SI)
has not attempted to change them.
