The diagonal fraction bar in mathematics . Also called virgule .
This symbol was used to replace , sometimes referred to as a
vinculum , due to the typographic difficulty imposed by the
horizontal bar which requires three terraces An early written
example of this usage can be found in a 1718 ledger by Thomas
Twining. In his article "The Calculations of Functions" from
1845 and published in the Encyclopaedia Metropolitana, De Morgan
recommended the use of the solidus. Also, an ancient Roman gold
coin used until the fall of the Byzantine Empire and introduced
by Constantine.