Nelson E. Ross's "small booklet" sets out the principles of sending telegrams "in the most economical manner possible," so you can take full advantage of a communications medium that "annihilates distance and commands immediate attention."
Telegrams were like early Twitter, with extreme length restrictions and obscure rules about what counted against them (Twitter lets you append up to four images for the same "price," while telegraph companies counted "20th" as three words, while "twentieth" was only one).
Proving there's nothing new under the sun, the guidebook instructs would-be-paleo-spammers on how to send out identical bulk spams:
Multiple Messages — If you wish to send the same telegram to 20 different persons, or 200, or 2,000, it is not necessary to prepare 20, 200 or 2,000 separate telegrams at considerable cost of time and money. You need only to make one copy of your message and furnish a list of addresses. At no additional expense, the telegraph company will prepare the messages for separate handling, with as much speed and accuracy as, if only a single message were filed. Such "books" of telegrams, as they are called, often are sent by business concerns in offering some special proposition to customers, or in the collections of accounts. The largest number of copies ever filed at one time by a single concern is said to have been more than 200,000 telegrams. They were sent from New York City. Such an avalanche of messages would put considerable strain upon the facilities of the world's metropolis, but fortunately several hours notice had been given and operators were held for emergency duty.
[Nelson E. Ross/Telegraph Office]