THE FIRST SUBMARINES Throughout human history people throughout have been curious about the underwater world At first explorers simply held their breath and dove in But they could only stay submerged for a few minutes before they ran out of air Around 3000 BCE Greek divers used hollow reeds to breathe under water They also carried bags of air These did not last long though Divers still had to surface quickly An Idea Is Bourne In 1578 William Bourne 1535 1582 an English mathematician and Royal Navy gunner published a book that described his idea for engineering a submarine However Bourne's submarine was never built
The diving bell gave early explorers another way to breathe under water These heavy containers were made of wood metal or glass Diving bells sank because the downward force of their weight was greater than the upward push of the water When the bells sank a bubble of air was trapped inside People could use this air to breathe Early Bells Legend has it that Alexander the Great 356 323 BCE used a type of diving bell in 332 BCE The modern diving bell was invented in 1690 by Edmund Halley Halley's diving bell was weighted down with barrels Tubes brought air to the inside of the bell
The first working submarine was invented by Corenelis Drebbel in 1620 The Drebbel looked like two rowboats stuck on top of each other People sat inside the Drebbel and used oars to row the craft Drebbel covered his craft with greased leather to keep water out This method did not work very well Drebbel put heavy weights inside his submarine These weights increased the submarine's density which made it sink He got rid of the weights to lessen the density and make the submarine rise A Trip under the Thames In 1623 Drebbel's watercraft carried 16 passengers under the River Thames in London The submarine stayed under water for about three hours but it did not go very deep
In 1680 Giovanni Borelli invented ballast tanks Borelli filled goatskin bags inside a submarine with water This made the submarine denser so it sank When he wanted the submarine to rise Borelli squeezed the water out of the bags In 1729 Nathaniel Symons invented a sub that could change volume to move up and down A handle inside the submarine pulled Giovanni Borelli the two halves of the ship together This 1608 1679 gave the submarine less volume and density so it sank When Symons wanted to return to the surface he turned the handle the other way The two halves spread apart Now the submarine had more volume and was less dense so it rose to the surface move up ballast filled with water empty ballast move down
