French instrument-maker whose signature appears on a prototype meter exhibited at the Museo Galileo of Florence (inv. 389, 3342). In two letters to Giovanni Fabbroni (1752-1822) discovered in the archives of the "Reale Museo di Fisica e Storia Naturale" of Florence (doc. no. 40 in Filza di conti dell'anno 1798 [Accounts file for 1798]), Francesco Favi describes Ferat as a maker of prototype meters and "other instruments for engineers and public schools."