The modern technologies we now enjoy were thought of long before most of us were born. Anyone reading popular science type magazines back then would have known about things like this. https://www.huffingtonpost.com/2015/07/10/tesla-quotes_n_7771358.html
I find it ironic, that while predicting the nearness of the end of the world in their own magazines, the folks at the Watchtower were simultaneously using information from "worldly" sources, to tout the availability of modern technologies they'd be using in the ministry, in a future that wasn't supposed to come about.
(P.S. Is it me or does the guy in the drawing look like a young Ronald Regan?)