design work there were many rules of proportion. One
often mentioned in reference to gun work is the "Golden
Mean." This proportion, which dates back to the art
the ancient Greeks, is 1 to 1.618 and that is the often
rounded off to 3 to 5. In modern use we have the 3X5
card and the 8 1/2X11 sheet of paper as reminders of the
The Journal of Historical Armsmaking
Technology, Volume II, 1987, has an article by Barry Bohnet that goes into some detail in explaining the
importance of proportion in design.
BELOW: A pair of modern dividers set at the three to
five proportion. Other ratios can be set by moving the
Dividers like these are available at drafting supply
houses and some college book stores.
In the tool catalog of John Wyke, from the third quarter
of the 18th century, the engraving shows very similar
dividers to the modern ones above. The old ones are
often made of brass, with steel tips.