Documents relating to Stephen Hales work on ventilators.

"Hales's experiments on air and respiration were the stimulus for the invention that more than any other contributed to his contemporary fame ... Hales's ventilators were installed in His Majesty's ships, in merchant vessels, in slave ships, and in hospitals and prisons ... As one of the first to call attention to the importance of fresh air, Hales deserves his reputation as a pioneer in the field of public health" (H. Guerlac, D.S.B.).