In the early days of typewriting, this was usually the first thing typed on each new typewriter after it rolled off the production line:
Amaranath sasesusos Oronoco initiation secedes Uruguay Philadelphia
A worker known as an aligner typed it to check that the resulting letters were aligned correctly on the platen.
How does it work? ‘Amaranath,’ the misspelled name of an imaginary flower, checks the alignment of the vowel ‘a’ between a number of common consonants. ‘Oronoco’ checks the ‘o’ key, while ‘secedes,’ ‘initiation’ and ‘Uruguay’ check three vowels that are among the most commonly used of all letters, ‘e,’ ‘i,’ and ‘u.’ ‘Sasesusos’ not only compares four of the five vowels in the same word against the baseline of the letter ‘s,’ but also ‘includes several of the most common letter combinations in twentieth-century business English.’ ‘Philadelphia’ checks the horizontal alignment of ‘i’ and ‘l,’ the narrowest letters on the keyboard.
What does “Amaranath sasesusos Oronoco initiation secedes Uruguay Philadelphia” actually mean? “Unlike most sentences, it was rarely spoken, and no one particularly cared what it might mean in the conventional sense.” (The “quick brown fox” came later.)
(From Darren Wershler-Henry, The Iron Whim, 2005.)