Dividers: Decorative Elements

 The design of tools is grounded in their function, but decorative elements add to their aesthetic appreciation. There are few antique tools that exceed early dividers in the degree to which artistic elements have been worked into what is ultimately a very simple tool. Tools from the 18^th century and earlier fall into two general categories. Everyday, utilitarian tools made by the user, or a local blacksmith are generally lacking in much decoration. Skilled craftsman and early, small shops produced pieces often showing a surprising amount of decorative detail. It’s probably safe to say that the more decorative elements a tool shows, the older it is. American made tools of any era show minimal decorations; English tools slightly more, while continental tools usually show the most. This applies to a range of tools such as wooden planes as well as marking and measuring devices such as dividers. Few sources highlight these ideas more impressively than Sandor Nagyszalanczy’s The Art of Fine Tools, 1998, Taunton Press. 

Decorative elements on dividers are generally focused on five areas of the tool:

-        Hinge joint

-        Wing nuts and thumb screws

-        Wing finials

-        Leg sculpting

-        Leg shape (mainly calipers)

-        Surface etching     

In this post I’ll give some examples of each of these from my collection. Far more impressive examples can be seen on sources highlighting museum collections (e.g. Museo Galileo) or web sites such as Jim Bode Tools, Fleaglass ,Tesseract and the wonderful French site Compas, dans toute leur diversite.  

Hinge Joints 

Not many examples exist in this category except for the concentric circles in the bullseye pattern characteristic of 18^th and early 19^th century “Lancashire pattern” English dividers (rt. below).

Bull'seye pattern on right

 Large eighteenth ccentury dividers, often called French armorer's dividers, can have very fancy extended hinge decorations.

French "Armorer's Dividers"

Closer view of above 

 Wing nuts and thumb screws 

A common and often whimsical design element in wing dividers. 

 

Heart, ram's horn and mouse ears thumb screws

Wing finials

Generally, a small artistic twist.  

Leg sculpting 

Usually, gouge-like chamfers in the upper legs, often file cut. Also, inscribed lines in thicker leg bosses (characteristic of Lancashire dividers).

 

A fine example with a range of filed elements

 Leg shape 

Most often seen in flat stock calipers. The best examples are “lady leg” or “dancing master” calipers. Those with detailed designs can be pricey.  

 

Lady leg calipers

Surface etching

 Not very common given the limited surface area on which to work. Etched owner’s names, as on one of the pairs of dividers below, can be quite fancy.

 

Dividers With Fine Adjustment

 For hundreds of years dividers and calipers relied on a single adjustment process to hold the legs in place. This usually involved friction at the main joint or a thumb screw bearing down on a wing. It’s unclear when a second adjustment step was added to the tool whereby the user could fine tune the spacing of the points once they were roughly set. This is almost always seen in wing dividers. My guess is this option became more common during the 1600’s. A 1709 print by Nicholas Bion shows a pair of wing dividers (“d” below rt.) with a fine adjustment wing nut attached to the end of the wing. If you look at the wing dividers in the painting “God the Geometer” from c.1250 there is a wing nut on the outside of one leg which could have been for fine adjustment. As you might predict, there are numerous ways that  fine adjustments were carried out. The focus of this post is to look at some of the ways this occurred. 

       

God the Geometer

                         

Bion: Mathematical Instruments

                          

                                           

Likely the earliest and most widespread technique to fine tune the points was to extend a rounded section of the otherwise flat wing through the leg opposite the leg with the locking wing thumb screw. If this protruding end was threaded, the wing could be moved a small distance in or out with a wing nut. For this technique to work effectively there needed to be a way to put pressure on the wing on the  inside of the fine adjustment leg. Typically, this was done by attaching a slightly curved piece of spring steel on the inside of the fine adjustment leg near the joint with the other end pulling on the wing, exerting a force opposite that of the thumb screw on the outside of the leg. This style has been in use for several hundred years. It’s common to find examples of dividers where this piece is missing or broken. 

                                                    

Sullivan's 1880 pat.
The most common form of fine adjustment

In some early dividers a second locking wing nut passes through the fine adjustment leg and presses on the wing extension within the leg and locks the wing in place once the fine adjustment is complete. In the second photo below the main wing locking screw is on the left leg and not visible.

                                                                     J. Stevens #61

J. Fenn, London, 1821-1873

A later development was to replace the curved spring steel piece with a small, coiled spring wrapped around the end of the thin wing extension which pressed against the inside of the leg and against a stop on the wider part of the wing. These variations are best understood by referring to the photos rather than my convoluted descriptions.                             

Starrett #85

                                                                                                                            

Stanley #57

                                             

What follows are a number of examples with various kinds of fine tuning mechanisms.

Unmarked with "roller nut"

W. Schollhorn "Pat. Appplied For"
The fine adjustment is on the left leg.

W. Schollhorn 1866 pat. +
1890 pat. for fine tuning on right leg + patented pencil holder

            

                                                                    Starrett #62

Early example with threaded insert in top leg

                                

           An interesting unmarked piece with an internal spring in the main joint to maintain tension.

        

               Likely a user made caliper with Rube Goldberg fine adjustment in the upper left

Rare to find wooden dividers with a fine tuning option
(doesn't work very well)

  

                                                                Starrett 1885 pat.

                                  Top thumb screw locks legs. Central knurled knob fine adjusts.

A final technique I'll mention for fine tuning dividers utilizes eccentric lower leg points. Since the points are not in a direct line with the legs above them, by rotating a lower leg one can change the separation of the points slightly. This can only work on dividers where the lower legs can rotate freely from the upper legs and lock . In the Stevens # 62 below the eccentric points provode a second fine tuning option that supplements the primary mechanism in the upper left leg.       

Eccentric points on a J. Stevens # 62, 1890 pat.