Ever wondered why we have the keyboard letters arranged as they are? A good article about the past of qwerty tells us why:
The first typewriter had its letters on the end of rods called "typebars." The typebars hung in a circle. The roller which held the paper sat over this circle, and when a key was pressed, a typebar would swing up to hit the paper from underneath. If two typebars were near each other in the circle, they would tend to clash into each other when typed in succession. So, Sholes figured he had to take the most common letter pairs such as "TH" and make sure their typebars hung at safe distances.
He did this using a study of letter-pair frequency prepared by educator Amos Densmore, brother of James Densmore, who was Sholes' chief financial backer. The QWERTY keyboard itself was determined by the existing mechanical linkages of the typebars inside the machine to the keys on the outside. Sholes' solution did not eliminate the problem completely, but it was greatly reduced....
Continue reading at the source: http://home.earthlink.net/~dcrehr/whyqwert.html