Manuscript, 'A conjecture concerning bladders of air that are found in fishes' by A I The author questions whether fish, 'by reason of the bladder of air that is within them', can sustain themselves in any depth of water. Includes one page of engraved figures. Subject: Zoology / Ichthyology Published in Philosophical Transactions as 'A conjecture concerning the bladders of air that are found in fishes, communicated by A. I; and illustrated by an experiment suggested by the Honorable Robert Boyle' May 1675