Michel Cadot Theodolite Dated 1740

Michel Cadot Theodolite Dated 1740





Michel Cadot

Country of manufacture


Categories: Surveying Instruments & Mining, Engineering antiques


I’ve updated my website to include ancient surveying instruments (1500 to 1800). The update includes a good deal of information related to the evolution of surveying instruments during that time period. The update also includes information regarding some of the important instrument makers during the period – this new section is still a work in progress however. Finally, the update includes 10 pretty cool ancient instruments for sale. 


You can access the evolution related pages at:  Ancient Instruments


And here are the ancient instruments I have for sale:  Ancient Instruments for Sale


Offered in this listing –  a WONDERFUL Theodolite made by Michel Cadot and dated 1740.


The fish on the side of the Theodolite represent Dauphins (Dolphins in English). The Dauphin of France was the title given to the heir apparent to the King of France. Putting a Dauphin on an instrument was a nod to the future King of France. I’ve seen a handful or two on instruments with Dauphins like this, and each one of those instruments was wonderful as well.

This Theodolite can measure angles to 10 minutes of a degree with the transversal/concentric circle arrangement. The Theodolite can function as a Surveyor’s Cross with the four fixed sight vanes each separated by 90 degrees. The Theodolite can also function as a Circumferentor/Surveyor’s Compass since the compass turns with the Alidade, making it possible to measure with the magnetic needle alone.

An instrument with transversals – the concentric circles – adds a lot of eye-appeal and interest to early instruments in my opinion. In theory a surveyor could read angles to ten minutes of a degree with this Cadot Theodolite. As Norwood pointed out at page 80 et seq. in his 1639 book on Fortifications, the mathematics behind the concentric circles and diagonals approach were fairly complicated, with many makers likely missing the mark. Over time most makers opted to use a vernier system instead of the concentric circle and diagonals system. Again, this makes for a really neat story if you display this Cadot Theodolite.

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 Macquart Paris 1740”. “Gendre de Maquart” means son in law of Maquart.

Please take a look at my 360 Degree View of the Cadot Theodolite (immediately below). You can Zoom in on any angle, so you can really see just how special this Theodolite is.

If you are interested in a bit more information about Michel Cadot and the instruments he made, please see my Michel Cadot Maker Webpage.

Finally, if you are interested in learning more about Theodolites made from 1500 to 1800, please see my Theodolites (1500 to 1800) Webpage. The Cadot is what I call a Second Generation Theodolite, so go directly to that page if you want to learn more about Theodolites made at roughly the same time as the Cadot Theodolite.



360 Degree View of Cadot Theodolite



You can see a 360 degree view of the instrument by clicking on the link below. You can ZOOM in for a High Resolution View of any angle.

You can control the Rotation and Zoom two ways:
(1) There is a control panel on the bottom left hand side. The arrows control Rotation and the magnifying glass controls Zoom.

(2) Your mouse can control Rotation and Zoom as well. You control Rotation by dragging the Mouse from side to side. You control Zoom with the scroll wheel. I personally prefer the Mouse approach.

360 Degree Spinner View – With ZOOM View

Ask the Dealer

Item enquiry

To enquire about this item, complete the form bellow to send a message to the Dealer

Enter Email
Confirm Email

Dealer information

US The Compleat Surveyor

The Compleat Surveyor specializes in rare instruments and books related to land surveying. This initially was a family business - my father (F. D. Uzes) was a noted surveyor, collector and author (Illustrated Price Guide To Antique Surveying Instruments and Books - published in 1980). Having spent a lifetime surrounded by old instruments and books, I now run the business myself. I use my website (www.CompleatSurveyor.com) to both sell instruments and provide historical information related to land surveying.

Shipping information
Payment methods
Terms & conditions