How Do You Date an E. Ingraham Clock?

Elias Ingraham had several partnerships during his years as a clockmaker. Each partnership led to a slight variation in the company's title. Identifying the name of the company can establish the clock's age within a few years. The first one or two stamped digits identify the month of manufacture. The next two digits signify the year of manufacture. These numbers together can give an exact year of age.