It is the development of this craft in connexion with the perfecting of flint-glass that makes the 18th century the most important period in the history of English glass-making.
Agricultural products require perfecting and fitting for export.
In 1804 Rich went to Constantinople, where, and at Smyrna, he stayed some time, perfecting himself in Turkish.
It was during this period that the genius of Robert Bakewell produced an extraordinary change in the character of our more important breeds of live stock, more especially by the perfecting of a new race of sheep - the well-known Leicesters.
The difference between the nymph or false pupa and the true pupa is that in the latter a whole stage is devoted to the perfecting of the wings and body-wall after the wings have become external organs; the stage is one in which no food is or can be taken, however prolonged may be its existence.