FROM THE DALE BEEKS COLLECTION

This is a beautiful 1825 Elijah Whiton Semi-Circumferentor - made in Groton Massachusetts. This wonderful instrument comes with its original box, and staff adapter. The instrument, box and accompanying pieces makes for an incredible display set. This Semi-Circumferentor checks all of the boxes when it comes to collecting - American made, rarely encountered, interesting features, great condition, and complete. Very obvious to me why Dale would add this special instrument to his personal collection.

This Semi is Serial Number 11. I know of 3 other Whiton Semi-Circumferentors and a couple of Whiton Compasses. I believe the highest serial number that I've seen so far is in the low to mid 30's. At Serial Number 4 this is the oldest Whiton instrument that I know about - I sold that one in 2022.

While Whiton's serial #4 semi-circumferentor indicates it is a Patent design, Whiton apparently never received a patent for this style of instrument. Note that this Whiton serial #11 does not have a Patent designation.

This Semi has offered several advantages over a traditional vernier compass. First, it can measure horizontal angles independently of the needle. And, second, it is setup to measure vertical angles as well.

I suspect that Whiton had really bad timing when he designed this wonderful instrument. Just a few years later William Young would develop his Improved Compass - what the NY makers called a Railroad Compass, which was a traditional surveyors compass that could also measure angles independently of the needle.

One last point is worth mentioning. Note the sight tube that runs underneath the semi-cirumferentor. The sight tube doesn't have any glass in it. But looking thru the sight tube gave the surveyor a nice way to really zero in on the target. A couple of the pics below show the sight tube.

Please note the crack in the main part of glass in the pics below.

Please see my Elijah Whiton Maker Webpage for more information about Whiton.

Also, please take a look at the 360 degree view with Zoom ability thru the link below.

360 Degree Spinner View - with Zoom Option
(Zoom with your mouse scroll wheel or with the magnifying glass in the spinner menu bar. Unzoom to regain control of the 360 degree spinner).