The way Leonardo da Vinci saw it, the problem with the canons of the time was that they took far too long to load. His solution to that problem was to build multi-barreled guns that could be loaded and fired simultaneously.
This idea forms the basis of war inventions like da Vinci’s 33-barreled organ, which featured 33 small-caliber guns connected together. The canons were divided into three rows of 11 guns each, all connected to a single revolving platform. Attached to the sides of the platform were large wheels.
All the guns on the organ would be loaded and then, during battle, the first row of 11 would be fired. The platform would then be rotated to properly aim the next row of canons. The idea was that while one set of canons was being fired, another set would be cooling and the third set could be loaded. This system allowed soldiers to repeatedly fire without interruption.
The weapon is referred to as an "organ" because the rows of canon barrels resemble the pipes of an organ. Leonardo da Vinci’s design for the 33-barrelled organ is generally regarded as the basis for the modern day machine gun – a weapon that didn’t really develop for commercial use until the 19th century.