author
1849–1918
A French-born American mechanical engineer and teacher, he wrote clearly for readers trying to make sense of big scientific ideas like entropy and the second law of thermodynamics. His surviving work has the feel of a patient lecturer turning difficult theory into something more approachable.

by Joseph Frederic Klein
Joseph Frederic Klein (1849–1918) was a French-born American mechanical engineer, educator, and technical writer. Sources found during this search connect him with teaching and engineering work at Yale, the Colt company in Hartford, and, for much of his career, Lehigh University.
He is best remembered as the author of Physical Significance of Entropy or of the Second Law (1910), a book that tried to explain one of science's most challenging concepts in plain, orderly terms. He also wrote Elements of Machine Design, showing the same practical, instructional bent in a more directly engineering-focused subject.
Because reliable biographical material on him is limited online, many personal details remain hard to confirm. What does come through clearly is the outline of a teacher-engineer who wrote to help students and general readers grapple with demanding technical ideas.