Tertie (angle)

Physical unit
Unit name	Tertie
Unit symbol	${\displaystyle {}^{\prime \prime \prime }}$
Physical quantity (s)	Flat angle
Formula symbol	Preferred angle names are Greek lowercase letters ( ) ${\displaystyle \alpha ,\beta ,\gamma ,...}$
dimension	${\displaystyle {\mathsf {{\frac {L}{L}}=1}}}$
In SI units	${\displaystyle \mathrm {1^{\prime \prime \prime }={\frac {2\pi }{77\,760\,000}}\;rad\approx 80{,}8\cdot 10^{-9}\;rad} }$
Named after	Latin pars minuta tertia , 'third diminished part'
Derived from	Arc second
See also: angular dimensions

Tertie is an obsolete angle unit for the sixtieth part of an arc second . It is indicated by three dashes attached to the number above:

z. B. 4 ° 9 ′ 25 ″ 10 ‴ = 4 degrees 9 minutes 25 seconds 10 tertiary.

The name is derived from the continuation of the sexagesimal subdivision minute (the 'diminished'), second (the 'second'), ... (from Latin pars minuta tertia , third diminished part ').

In nautical practice, this unit is still used despite its antiquity and the increased use of decimal divisions. One example of this is its use as a meridian measure for travel measurement with rail logging in ship navigation .

See also

• Tertie (unit of time)

Individual evidence

1. ↑ Johann Schultz: Short teaching term of mathematics. For use in lectures and schools. Königsberg 1797, p. 185, view in the Google book search