In the 19th century the textbook dominated the curriculum and methods of instruction. The most important textbook was the textbook of reading known as the reader. In the early 1800s science was not established as a separate primary grade subject. The science students encountered in these reading textbooks may have been their only formal science education. This study used content analysis to determine the type of science and the quantity of science in popular U.S. readers of the 19th century. The percent of science rose in the middle of the century and declined at the end. This decline may have been due to the desire to make the study of reading literary based. The percentage of science that was biological increased throughout the century, and the percentage of Earth science declined. (Contains 2 figures.)