OK all you sharp tacks out there! Care to take a guess at this one?
There is a specific name for this tool although it was somewhat similar to another well known tool.

The divisions are for when the plumbnity of a larger machine was being checked (they were not needed for fence posts, of course). Then, one needed to know exactly how much correction was needed. While it is only divided into three degree increments, verniers were used to get accuracy to one fourth of a degree.

It is amazing what you can find on the internet, isn't it!

Mr Lo, or ehm Huang, which ever it is you are.

The tool is indeed an Inclinometer. This one caught my eye since it was less resembling of just an improved level which many of the other makers derived their products in design. The inclinometer, also helped lead to other developments with builder’s levels and transits.

This tool was made by the Patent Level Company.

"The Patent Level Company - was located in Bridgeport, Connecticut according to the stamp on the base of the level. To date, however, no other record of the existence of this company has been found. The patent date - May 8, 1866 - corresponds to the date on which a patent was granted to Andrew. J. Vandergrift of Cincinnati, OH, for an "Improvement in Spirit Levels." "

It's really a bad picture of the tool thats the problem.

Check out this site for some nice info on level's and kin

• http://www.antiquetools.com/levels/index.html