author
b. 1874
A Norwegian-born mathematician and textbook writer, he helped make geometry and algebra more practical and approachable for students in the early 20th century.
Born in 1874, N. J. Lennes was a mathematician and educator best known for writing clear, classroom-focused books on geometry, algebra, and arithmetic.
His work appears in major public-domain collections today, including Project Gutenberg, where many of his textbooks have been preserved. The surviving record available here points to him primarily as a teacher and author whose books were designed to help students build solid mathematical habits through practice and application.
I couldn’t confirm enough reliable biographical detail in the sources I found to go much further than that, so this overview keeps to the basics.