Complex sentence: From 1847 to 1856 he was engaged in teaching chemistry at the Polytechnic, of which from 1883 to 1892 he acted as director, and from 1856 to 1866 he was on the staff of the military high school.
Split into simpler sentences: From 1847 to 1856 he taught chemistry at the Polytechnic, where from 1883 to 1892 he was the director. From 1856 to 1866 he was on the staff of the military high school.