In this period Britain dominated the world with her use of Feet and Inches. The USA followed suit and to this day still uses Feet ‘ and Inches”.
If you want to use period tools they are always designated in feet and inches and it is wise to get used to using these units.
It is important to note that this measurement system relies on fractions. So an inch is divided into eighths which are subdivided into sixteenths and thirty seconds. Half an eighth is two sixteenths etc. For many uses such as fitting drawers this use of fractions is very helpful.