The 18th century is often referred to as the "Age of Reason and Change." The first Industrial Revolution began in 1712 when Newcomen's Steam Engine was installed in the Dudley Castle Coal Mine, and in 1728, Russian Explorer Vitus Bering explored the area we know today as the Bering Straits. Paul Revere, Martha Washington, and other famous figures were born, and in 1751, Benjamin Franklin invented the lightning rod. The American Revolution and the Jacobite Rebellion took place; and all the while, things were happening underwater.
Early Diving Systems
By the second half of the 18th century, crude but somewhat successful diving systems were being developed. One of the most interesting was the "Hydrostatergatic Machine," brainchild of a French inventor named Freminet. Its main feature was a brass helmet, complete with glass-covered eyeholes. Air was supplied by bellows at the surface, which were used to pump breathable air into a reservoir, which in turn was utilized by the diver. It was intriguing; but it was of limited use as movement and air consumption were restricted. Later, in 1786 and 1787, two improved versions of the helmet were developed; these, and diving bells, were used for some time.
Diving Bells
Diving bells were used during the era of Alexander the Great, well before the Common Era began. Until the late 1600's, they remained extremely primitive devices which held only a certain amount of air. A scientist named Sir Robert Boyle made important discoveries concerning the behavior of gases placed under pressure, which today we recognize as Boyle's Law; this research led to great strides in underwater capabilities. More sophisticated diving bells were designed by John Lethbridge, a commoner hailing from Devon, England, and by Sir Edmond Halley, a famed English astronomer, for whom Halley's Comet is named.
Lethbridge's "Diving Engine" allowed divers to submerge to a depth of about 60 feet for as long as half an hour; the diver was contained inside a sealed cylinder with his arms free to work. The engine could be hauled up periodically, and new air could be added to it with a bellows. The apparatus was used with excellent success by salvagers working for the Dutch East India Company.
Halley's design was more like a traditional bell, but it was fitted with a valve for purging stale air and a system of weighted barrels connected to the surface with a hose, which allowed the bell's air supply to be replenished while submerged. Divers could even wear a helmet and an umbilical to leave the bell for short periods of time, thus greatly increasing efficiency. Halley wrote of diving to a depth of 60 feet in this bell and staying there for 90 minutes; he experienced pain in his ears "as if a quill had been thrust into them," but he made no mention of any symptoms resembling DCS despite the fact that his bottom time was well in excess of no-deco limits.
Later diving bells used continuously refreshed air supplies fitted with hoses and bellows, air reservoir systems, and no-return valves By about 1788, when an American named John Smeaton made those final improvements, working underwater became a common occupation; every major harbor was equipped with a modern diving bell.
It wouldn't be until about 1820 until more modern diving systems were invented. Diving Bells are still used today, though; commercial divers use wet bells and closed bells for a number of applications. Our modern dive bells and underwater hyperbaric chambers would probably not exist, nor would our modern scuba gear, if not for the ingenuity and bravery of the inventors who came before us.