Cross section view of the diving bell designed by Edmond Halley (1656-1742). The bell was made of wood, with the outer side covered with lead. At the top (AB), a strong glass panel was fitted to let the light in. A valve (R) was used to periodically let out stale air. The plaform (GH) where the diver was supposed to stand when working was kept steady with weights. The air could be renewed thanks to barrels of compressed air (E) sent from the surface.
The diver walking the seabed (X) illustrates the most experimental part of the device: intended to increase the mobility of the divers and broaden the range of their action, it consisted of a smaller bell made of sheet metal worn as a helmet, and though the author warns about how dangerous this would have been, he doesn’t make it clear it was ever actually used.
The caption reads in the original French:
Cloche de Halley.