Have a look at some change in your pocket and you’ll see that mostly coins have ribbed edges as if they are scarred. Such textured surface can be observed in almost every coin of the world no matter where it came from. Such coins appeared several centuries ago. So why are all of them ribbed?
Have you ever wondered why the letters on any keyboard (of your PC, tablet or laptop) aren’t situated in alphabetical order? The location of letters goes back to 19th century typewriter. The principle of its work is very simple. When you push the button with the letter, it activates a small type lever with a cast matrix of this letter on its top. This type lever hits the ribbon soaked with ink, which occupies the position between lever and paper. This is how we get the print. While typing a text, levers hit the paper one by one. Continue reading
