Complex sentence: Up to about twenty years of age Forde was principally engaged on works of a decorative character painted in distemper; in 1826 he was able to execute works of his own invention, and give expression to the grand projects which his poetical mind conceived.
Split into simpler sentences: Up to about twenty years of age, Forde was principally engaged on works of a decorative character painted in distemper. In 1826 he was able to execute works of his own invention, and give expression to the grand projects which his poetical mind conceived.