Hydraspis, or Water Shield
Personal floatation device invented by the seventeenth-century German polymath Johann Christoph Wagenseil. Equipped with hinges—so that the user could insert himself into the circle and then securely reclose it—Wagenseil’s invention was to be used with “water-sandals” that approximated the webbed feet of waterfowl. His design included two covered compartments on the device’s top surface in which a shipwreck victim could stow “a quantity of food sufficient for a long time, or . . . money, writings, or other valuable things” while awaiting rescue.
By the eighteenth century, the belief that science could be used both to save lives and to preserve valuable ships and cargoes inspired interest in lifesaving devices, as well as in improvements in marine architecture.