I have collected old technical manuals from the 30’s, 40’s and 50’s since I was a teen and have read through and learned from every single one of them. now retired I have even more time to find more and read more of them. one of the fascinating things about the tech manuals of the past is the advanced language and math built in to each one of them expecting that the reader already possesses the education level needed to understand the material . the MOST fascinating thing all to me is the fact that these highly technical manuals that many college grads of today would struggle to understand were written for the AVERAGE high school graduate. yes folks...the people who designed the bridges, skyscrapers, flying machines and the vast array of warfighting machinery that won WWll were educated LONG before the Carter.
Your tech manuals parallels my experience articles in research journals during the 60’s and literary level requirements in the same journals today. In the past compound sentences are often used to explain the theories and results. While today the requirements are fourth grade reading level.
In my opinion each advancement back then were far deeper than ones today.