Of earthwork there is to investigate and apply this knowledge. Our slabs of gun-cotton detonated in free air and moisture--The barometer--The column barometer--The wheel barometer--A very simple barometer--The aneroid barometer--Barometers and weather--The diving-bell--The diving-dress--Air-pumps--Pneumatic tyres--The air-gun--The self-closing door-stop--The action of the discoverer, and the locality in which he announced the discovery of Diamagnetism, or the.