In his initial study, Braille had experimented with geometric shapes cut from leather as well as with nails and tacks hammered into boards. He finally settled on a fingertip-sized six-dot code, based on the twenty-five letters of the alphabet, which could be recognized with a single contact of one digit. By varying the number and placement of dots, he coded letters, punctuation, numbers, diphthongs, familiar words, scientific symbols, mathematical and musical notation, and capitalization. With the right hand, the reader touched individual dots and, with the left, moved on toward the next line, comprehending as smoothly and rapidly as sighted readers. Using the Braille system, students were also able to take notes and write themes by punching dots into paper with a pointed stylus which was aligned with a metal guide.