An artificial gill that mimics the way fish breathe could allow divers to dispense with bulky tanks, was claimed recently. The device, which has been developed by an Israeli engineer, could also be used to supply air to submarines and underwater hotels. The device, which was designed by Alan Bodner, consists of a lightweight cylinder containing a centrifuge. Water passing through the device is rapidly spun and thrown to the outside of the cylinder, leaving a vacuum in the middle. The drop in pressure releases dissolved air, which is collected. The invention has already attracted interest from the Israeli navy, as well as from diving equipment manufactures. The âgillâ is best suited to closed-circuit diving, where exhaled air is continuously recycled by cleansing it of carbon dioxide and adding oxygen.