Natural speed, please.
When he had so said he left her and went to his bellows, turning them towards the fire and bidding them do their office. Twenty bellows blew upon the melting-pots, and they blew blasts of every kind, some fierce to help him when he had need of them, and others less strong as Hephaestus willed it in the course of his work. He threw tough copper into the fire, and tin, with silver and gold; he set his great anvil on its block, and with one hand grasped his mighty hammer while he took the tongs in the other.