I've come across a bunch of 7"x10" magazine-type publications called "The Mentor" from 1913. Each one is printed on heavy paper and addresses one subject. They were published twice a month and the subscription price was $3.00/year. One of them addresses Great American Inventors and includes six "intaglio-gravure pictures" of inventors like Elias Howe, Thomas Edison, etc. Can anyone tell me anything more about these publications?