"For this [ventilator] invention Triewald was granted a privilege for life by the King and Senate of Sweden. He then wrote a "deduction" on the usefulness of ventilators... distributed among... naval officers. This "deduction" was read before the Royal Society in 1742. In it Triewald recommends the use of ventilators "in Hospitals and Barracks for the sick, Men-of-War and Hospital Ships.""