The telegraph operators of the early 20th century had a rich vocabulary of wrist-saving abbreviations they used among themselves: "Is tt exa tr et?" ("Is that extra there yet?")
They're documented in The Telegraph Instructor, written by George M Dodge and published in 1901 to help aspiring operators get hep to the jive.
Dodge, author of The Telegraph Instructor, intended his book to be an easy-to-follow instruction manual for aspiring operators. Dodge worked as a telegrapher for the Pittsburg, Fort Wayne, & Chicago Railroad, began teaching in 1874, and expanded the scope of his school at the end of the 19th century. By 1910, Dodge boasted to prospective students in an ad at the back of Popular Mechanics that his Institute of Telegraphy, in Valparaiso, Indiana, was “the leading telegraph school in America and the only one graduating thoroughly practical operators.”
"U Tr?": A Glossary of Abbreviations Used by Early-20th-Century Telegraph Operators [Rebecca Onion/Slate]