Sholes and Glidden typewriter length. The redesigned platen also introduced the modern spacing functionality (horizontal and axial movement providing letter and line spacing, respectively). The cylindrical platen became "an indispensable part of every standard [typewriter]". By the end of 1872, the appearance and function of the typewriter had assumed the form that would become standard in the industry and remain largely unchanged for the next century. Although the machine possessed a cylindrical platen and what was essentially a QWERTY keyboard, two design elements that would later become essential were lacking: the ability to write in upper and lowercase letters and "visible" print. Although the
Cylindrical drum Cylindrical drum Cylindrical drums are a category of drum instruments that include a wide range of implementations, including the bass drum and the Iranian "dohol". Cylindrical drums are generally two-headed and straight-sided, and sometimes use a buzzing, percussive string. The Iranian "dohol" is a famous form of cylindrical drum. Many music areas nears in the Middle East, North Africa and Central Asia include variations on the dohol and cylindrical drum forms, including the "dhol" of Armenia, "daval" of Kurdistan and the "tabl ballady" of Egypt. Southeastern Europe is home to cylindrical drums like the "tapan" of Macedonia and the "dauli"