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
Typewriter in the Sky Science Fiction Source Book" (1984), "His [Hubbard's] best work is outstanding within the pulp tradition: "Typewriter in the Sky" is a fine fantasy about a man who gets trapped within a story written by a pulp writer". The book is listed in "Fantasy: The 100 Best Books" (1988), by James Cawthorn and Michael Moorcock. Robert E. Weinberg, Stefan R. Dziemianowicz, and Martin Harry Greenberg write in "Rivals of Weird Tales: 30 Great Fantasy and Horror Stories from the Weird Fiction Pulps" (1990) that "Typewriter in the Sky" is classed among stories published in "Unknown" which "still rank as some of