SHOWCASE 15

At the left, there are two English books devoted to Telephones and Telegraphs. The first of them is "Field Telephones and Telegraphs. For Army Use" (London, 1917). The second book is "The Elementary Principles of Wireless Telegraphy" by R.D. Bangay. That one was published in London in 1914. 

At the right, there is "Harper's Wireless Book" by A. Hyatt Verrill published in New York and London in 1913.