Brass Compass And Clinometer

After extensive research we have found 2 different names for this and two different but similar uses. It is a brass compass and clinometer or inclinometer. It can measure hills or waves. It is an engineering or geological tool or a ship's compass. It might also be called a Theodolite. It is branded "E.R. Watts & Son- London Eng, Ottawa and Winnipeg" I believe it is approximately late 1930's -early 1940's. Our Grandfather was an engineer, and so we assume this was his. It is in excellent condition and seems to work just fine. It does not still have its original case.