We all know that Leibniz introduced the differential notation $dx, dy$, and that in developing his calculus for infinitesimal differences he was inspired by his previous work on finite diffences. Today we usually denote such finite differences $\Delta x, \Delta y$. But did Leibniz use this notation? If not, who originated it?
According to Florian Cajori, A history of mathematical notations (1928 - Dover reprint) :
"A provisional, temporary notation $\Delta$ for differential coefficient or différences des fonctions was used in 1706 by Johann Bernoulli." (see Cajori, page 205 of 2nd vol).
L.Euler introduced the symbolism for finite differences in Institutiones calculi differentialis (Petersburgh, 1755), p.3-7 (see Cajori, page 265).