What is the title of Lewis Carroll's 1879 book critiquing non-Euclidean geometry?

Lewis Carroll’s 1879 book critiquing contemporary geometry textbooks is Euclid and His Modern Rivals.

Written by Charles Lutwidge Dodgson under his pen name Lewis Carroll, the book defended Euclid’s Elements against newer geometry textbooks that were replacing it in Victorian education. Dodgson was an Oxford mathematician and had taught geometry for many years, giving him a practical interest in how the subject was presented to students.

The work is unusual in form: rather than being a conventional mathematical treatise, it is a humorous dialogue or drama. Euclid’s ghost helps Minos assess the competing textbooks, while Professor Niemand acts as the advocate for the modern alternatives. The arguments address definitions, proof structure, constructions, and the treatment of the parallel postulate.

The title is sometimes confused with Carroll’s other mathematical and logical works, including Symbolic Logic and The Game of Logic. Despite its comic style, the book is also a valuable record of nineteenth-century debates about geometry teaching.