A description of ventilators : whereby great quantities of fresh air may with ease be conveyed into mines, gaols, hospitals, work-houses and ships, in exchange for their noxious air : an account also of their great usefulness in many other respects, as in preserving all sorts of grain dry, sweet, and free from being destroyed by weevels, both in grainaries and ships, and in preserving many other sorts of goods : as also in drying corn, malt, hop, gun-powder, &c., and for many other useful purposes /