Michel Cadot apprenticed to the famous instrument maker Delure in 1718 in the Founders' Company. Cadot was the son-in-law of, and successor to, Henry Macquart (who was a well-known maker of instruments as well circa 1700). My Cadot Theodolite is signed "Cadot Gendre de Maquart Paris 1740". "Gendre de Maquart" means son in law of Maquart.

A handful of Michel Cadot instruments are known - Cadot made some nice instruments based on the link. My Cadot 1740 Theodolite is the only surviving surveying instrument. I suspect Cadot made others - the 1740 Theodolite would be a VERY challenging first surveying instrument to make.

The only Cadot instruments I could find on the internet are smaller things as pictured below.

I believe that Michel Cadot stopped making scientific instruments in the early 1750s.