The Puckle gun was invented by a London based lawyer named James Puckle, who had an interest in firearm design. He received a patent for his design in 1718.
Part of the patent application for the Puckle gun. Public domain image.
This was a flintlock firearm fitted with a multishot cylinder, much like a revolver. The cylinders were designed to hold 11 shots at a time. Unlike revolvers, there was a manual crank attached to the back to bring each chamber of the cylinder to the firing position. It was mounted on a tripod and the barrel was about 3 feet (0.91 meters) long. The caliber of this weapon was 1.25 inches (32 mm.). Typical of the era, the firearm came with bullet molds to cast bullets for it (part #21 in the above patent application).
This weapon was supposed to be used as a defensive weapon. If you look at the patent flier sheet above, the weapon is advertised as "A Defence" and the tagline below the title reads: "Defending KING GEORGE your COUNTRY and LAWES / Is Defending YOUR SELVES and PROTESTANT CAUSE". Below the drawing of the gun, it says that it is intended for use in "bridges, breaches, lines and passes, ships, boats, houses and other places."
A very interesting and unusual part of this design are the parts labelled 16 and 17 in the figure above (and also 18 and 19, which show a single chamber of 16 and 17 respectively). It shows the plan of two cylinders used by this rifle. Notice that the shapes of the holes in the two cylinders are different. This is because the gun was designed to fire two different shapes of bullets and the patent document elaborates how they were to be used. The cylinder that fires round bullets was designed to be used against Christian enemies and the cylinder firing square bullets was intended to be used against the Turks, who were Muslim. Apparently the square bullets were considered to be more damaging and the patent document explains that using square bullets against the Turks would 'convince them about the benefits of Christian civilization'! These days, such views would be considered quite inappropriate and racist, but views were a bit different back in the 1700s when this firearm was invented. Incidentally, the square bullets had to be discontinued soon afterwards, because they had a tendency to fly erratically through the air.
Another general point of interest about this patent was that it was written shortly after a change in British Patent law. The new patent law stated that the inventor must describe the invention and how it works in writing, in order to be considered for a patent. This gun's patent documentation was one of the first ones to do it as per the new patent law standards.
While the Puckle gun was an interesting design, it never was a huge success. Part of the problem was that the design had many complicated components and most British gunsmiths didn't have the necessary skill-sets to easily make these parts. Even though it was a commercial failure, the gun was way ahead of its time. It was the precursor to modern machine guns as well as revolvers.