In this study, two major introductory calculus-based physics textbooks were compared for their linguistic and structural properties. Also studied was the evolution of a textbook from the third to seventh edition. The readability of each textbook was measured using a standard readability formula. A mathematical readability formula was developed to characterize the readability of texts that contain significant amounts of mathematics. The mathematical readability of each textbook was measured using the new formula. The mathematics in each textbook was also characterized by comparing the number of math words to the number of textual words. The linguistic richness of each book was measured using LEX. The allocation of page area to major textbook components was also investigated.