This collection of type specimen pages, published in 1910 by the Keystone Type Foundry of Philadelphia, demonstrates the appearance of the company's type when used to produce headlines of various sizes. In the foundry's choice of demonstration headlines, a strangely poetic vision of daily life in 1910 emerges.
The Keystone Type Foundry, like other vendors of type, published specimen books to illustrate its wares and distributed them to printers who were choosing equipment. The company had outposts in New York, Atlanta, Chicago, Detroit, and San Francisco (as well as Philadelphia), but clients who lived outside of major metropolitan areas could order supplies by mail.
Here's another Keystone specimen book, from 1906, viewable via the Internet Archive. It contains examples of Keystone's available page ornaments, borders, and cuts (standard illustrations that were the rough equivalent of today's clip art), as well as its range of type.
I found these pages on the Tumblr of the University of Wisconsin-Milwaukee's Special Collections.