So what’s the draw of dividers (no pun intended)? These tools have been in
use in the West since at least Roman times and likely far earlier in China.
They show a wide diversity of designs despite being basically a hinged pair
of legs. Dividers show up as elements in many paintings and etchings and
have a long history of symbolic use, the Masonic compasses and square being
a well-known example. They are not a tool that generally receives a great
deal of hard use so many early examples still exist especially in the UK and
Europe. Dividers and calipers have been used in dozens of occupations and
professions. They have been the subject of hundreds of U.S. patents, many
very complex and never produced. Acquiring examples of those that were
manufactured is an ongoing challenge.
In this blog I will use the terms dividers and compasses synonymously. I
consider compasses as dividers where the end of one leg holds a pen or
pencil. Keep in mind that numerous examples have exchangeable points so a
pair of dividers can often be turned into a pair of compasses. Calipers are
basically dividers where the lower legs are bent in or out to take outside
or inside dimensions. By convention dividers, compasses and calipers are
written in the plural. I will generally use the term dividers keeping in
mind that the reference often applies as well to calipers.
These tools typically fall into three broad categories: friction dividers,
wing dividers and spring dividers. All three have been in use for hundreds
of years. My collection and research focuses mainly on the first two. Most
of the examples available to users and collectors are relatively recent
machinist’s spring dividers as pictured below (right).
A few things to watch out for before you buy. The most common issue with
wing dividers is where the thumbscrew which secures the wing is either
missing or has an inappropriate replacement, often a slotted machine screw.
If the wing dividers are ones with a fine tuning option, make sure wing nuts
and other components are present. Someone who is competent with a file can
turn a pair of undecorated dividers into something quite fancy with notches
and hollows. Fanciful flat lady leg calipers have been known to evolve from
less curvaceous origins with the help of a metal saw or file.
The subjects of these blog posts on dividers will be wide ranging including variations in construction, decorative elements, patented models, references in art and philosophy and often a mystery waiting for a reader's solution. Occasionally I might even stray into discussions of other antique tools, especially dealing with "what's its".
If you also are a collector of dividers then you can call yourself by a fancy name, a "circinusophile", circinus being Latin for dividers.
Wing Dividers - Anatomy:
The above illustration lists the terms I will try to use when discussing
dividers. There are synonyms for many of them,
Some Uses for Dividers:
1. providing equally spaced points (dividing)
2. transferring measurements (e.g. from drawing to work piece,
maps)
3.
proportional measurements (drafting scales)
4. use with rules (e.g. Gunter’s, diagonal scales, sectors)
5.
scribing: match for uneven surfaces (e.g. wall edges)
6.
inscribing circles and arcs (compasses)
7.
geometric shapes: marking angles with the help of a
straightedge
Today's Mystery Tool
A pair of relatively new 11" dividers searching for a function. The circular object on the right leg is a rotatable bullseye level.
Mystery tool looks like it might be a log scriber, used to mark logs to fit them together for log buildings. The level would assist in keeping the dividers at a consistent orientation when scribing the logs.
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