The Circumferentor Playing Card Circa 1700
Circumferentors (aka - Surveyor Compasses)
"Circumferentor" was the original name for a Surveyor's Compass. Unfortunately, auction houses and a few museums now use the term "Circumferentor" to refer to a different instrument - a two or four vaned full circle which has a magnetic compass sitting in the middle of the full circle (this instrument was originally called a "Theodolite"). I'm going to use the original definitions for my website. So for my purposes, a "Circumferentor" is a "Surveyor's Compass" - an instrument with a fixed alidade (typically running North and South) that takes bearings with a magnetic needle.
My research indicates that England was the first European country to produce and use Circumferentors in a meaningful way. From what I can tell, Cirumferentors/Surveyor's Compasses were not made in quantity in Continental European countries. Circumferentors, with their ability to take bearings, were especially useful for surveys where there were no local landmarks. Which is why Circumferentors became especially useful and popular in Ireland and the Americas.
To my surprise, my research also indicates that First Generation Circumferentors were made out of wood, not brass, with a very interesting form factor. These early Circumferentors date to the early 1600's, if not earlier. The Second Generation of Circumferentors look much more like a standard American Surveyor's Compass, and started appearing in the mid to late 1600's.
The First Generation Circumferentor Design - 1600s
Three of the leading English surveying texts all describe the First Generation Circumferentor the same way - Rathborne in 1616, Leybourn in 1653, and Eyre in 1654.
The three authors state that a Circumferentor is about 8 inches long and 4 inches wide. The Circumferentor has two sighting vanes, one which is 7 inches high, the other which is 3.5 inches high. The upper side of the Circumferentor has a compass about 3.5 inches in diameter. Rathborne and Eyre say that the Circumferentor is made out of wood, whereas Leybourn doesn't say what the Circumferentor is made out of. The three authors agree on most of the lesser details as well. To my eye, Eyre's 1654 description looks to be a copy and paste job of Leybourn's 1653 description, with Eyre simply adding in that the Circumferentor is most usually made out of wood.
I scoured the internet looking for a First Generation Circumferentor, and I think I found one. Take a look at the pics immediately below. This Circumferentor sold on eBay in 2016, and it lines up nicely with the description of the Circumferentor found in the three early texts.
The Second Generation Circumferentor Design - Circa 1650
The Second Generation Circumferentor Design looks much more like the traditional American Surveyor's Compass. I suspect the Second Generation Design replaced the first pretty quickly, starting sometime around 1675 or a bit before. The oldest dated brass Circumferentor I found was an Irish Compass made by W. R. in Dublin and dated 1667. A small pic of that compass appears below to the left. . I do not know when American makers starting making Second Generation Circumferentors out of wood. I don't recall seeing any American wood compasses that date before 1700.
I believe that most of the Second Generation Circumferentors were made in 3 Countries - England, Ireland and America. I suspect many of the English Circumferentors were exported other countries, like Ireland and America.
Most of the early Irish Circumferentors seem to have a multi-part alidade (as shown in the Lewis Compass below). Click here to see an assembled early Irish Compass.
One interesting thing to note about the Lewis Compass below - East and West are reversed. In 1688!!! Wow.
For more information about early American Surveyor's Compass - Please Click Here.
Collectability
I would love to find and own a First Generation Circumferentor, but I only found the one eBay instrument, so there probably are very few that survived the last 400 years (especially since they were made out of wood).
Second Generation English and Irish Circumferentors pop up occasionally, and always sell at a discount compared to American Surveyor's Compasses. Almost all of the Irish and English Circumferentors have the same traditional compass face engraving design, so the compasses don't offer much in the way of variation. While a VERY early Irish or English Circumferentor would be interesting to own (like the one shown in the Playing Card at the top of this webpage), I suspect that most Irish and English Circumferentors are not very collectable. Which is why they sell at a discount to American Surveyor's Compasses.
Important Books - Circumferentors
Below are some of the important books related to Circumferntors.
The first three books are by Rathborne (1616), Leybourn (1653, but linked to 1657 edition) and Eyre (1654). These books all describe the First Generation Circumferentor.
Another interesting book related to the Circumferentors is Bion's landmark Mathematical Instruments book, first published in French in 1709. Edmund Stone translated this important book into English in 1723, and a digitized copy of the 1723 book appears below. The English version is a must have book for instrument collectors. Bion's French edition doesn't mention Circumferentors, but Stone added a section of Circumferentors when he translated Bion's book into English. Stone describes how to make and use a Second Generation Circumferntor in his book starting at page 126.
Finally, the 1982 Whipple Catalogue "The Compleat Surveyor" has a nice write-up on Circumferentors. You can read the write-up here.
Bion's Mathematical Instruments - Stone's English Edition (1723) - Showing the Second Generation Circumferentor (Fig G).
Note - Stone Added the Circumferentor Section; Bion's Book Doesn't Mention Circumferentors
My Reference Materials
Here are the main reference books I used while researching my Ancient Surveying Webpages:
5-Volume Catalogue Of The Most Important Worldwide Private Collection Of Scientific Instruments (With 928 Color Illustrations). Written in German, but an amazing reference tool. The pictures are incredible - most of the instruments are not found on the internet. Crazy Expensive.
Bennett's Catalogue of Surveying and Related Instruments (2022). Fantastic pics and info about the surveying related instruments at the Galileo Museum (which has an INCREDIBLE collection of early instruments).
Bennett's The Divided Circle (1987). A History of Astronomy, Navigation and Surveying Instruments.
Delalande Antiques Two Volume book series on Astrolabes. The two volumes walk you thru how to use and collect Astrolabes. A must have if you want to collect Astrolabes.
Kiely's Surveying Instruments - Their History (1947) Somewhat dated now, but still has a great deal of relevant information. Not the easiest read, however.
Daumas' Scientific Instruments of the 17th and 18th Centuries (Translated into English 1972).
Richeson's English Land Measuring to 1800 (1966). A nice book that is mis-paginated unfortunately. But still contains some good information about early English land surveying.
Important Websites where you can use the search function (e.g. "Theodolite") to find instruments:
The Museo Galileo Virtual Museum - A Stunning Collection of Early Surveying Instruments
The Science Museum Group (UK Based)
Harvard University Collection of Scientific Instruments
The Museum of History and Science, Oxford
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