Obviously with the invention of the sealed tin can, a method had to be devised to open them. The can opener first appeared in an edition of Britain's Army and Navy catalogue in 1885 and possibly the earliest domestic can opener was the `Bulls Head' type. This was a sharp pointed blade with a grip handle, which could be lodged onto the rim of the can, and pressure applied so that the point would pierce the metal lid. An up and down levering motion was used so that the metal lid would be prised away. This was dangerous as very jagged edges were left around the edge of the can, and soon the modern day can opener was produced.
The modern day can opener is a very simple but practical device. It has an extremely sharp cutting blade (or wheel) that pierces into the lid of the can. Positioned beneath the lip of the can is a toothed wheel which rotates manually. This causes the cutting wheel to be driven into the lid. In addition, there are two more toothed wheels which are located one above the other, which form a pair of spur gears. These transmit the turning force from the handle and allows the lid to be fully opened.
