There are slides devoted to this topic: Lecture 5b, pp. 12-28.

Websites

Check out the Computer History Museum‘s Calculators exhibit, which covers the evolution of mechanical calculators from from the 1820 Arithmometer to the keyboard-driven models of the early 20th century.  

Take a look at the “Calculating Gadgets” section of History of Computers, which has information on the important calculators of the era. 

Videos

Watch “How the Comptometer Works” to learn about the mechanism operation of the first practical, key-driven calculator. The video is detailed (if slow-moving), and features digital animations of the gears and parts in motion.

Books

Computer: A History of the Information Machine, Martin Campbell-Kelly and William Aspray, pgs. 29-32

The Universal History of Computing, Georges Ifrah, pgs. 127-142 (Evolutions in mechanical calculators; for information on electronic calculators, see pages 142-150)