FOR THE RECORDCopyrights and patents have always had an expiration date. Any published book copyrighted prior to January 1st, 1923 is in the public domain. In fact, anything published before 1964 is in the public domain unless it was renewed.This applies only to books copyrighted and published in the United States. Every other nation will have it's own set of quirky laws.
That means that I can painstakingly scan in high resolution all 52 pages of a chapter on wireless from a book in the public domain. Then wrap it up nice and tidy into a .pdf for your enjoyment for you to download. The book is the 1916 edition of the American Boys Book of Electricity by Charles Homer Seaver published in 1916.
The book focuses on the basics of wireless. It also includes a very detailed section on building and using a wireless set that is highly functional but composed entirely of hand-made parts. I've uploaded in a few places for redundancy. You can download this chapter, illustrations and all here.