First a little design background on drawer progression or what is often called graduated drawers. You are correct that it was a common practice to make each drawer narower than the one below it by the width of one drawer divider. The reason behind it again goes back to classical design. In the classical tradition, especially when stacking multiple elements vertically, you generally want to avoid identical shapes, one on top of the other. For example, a modern file cabinet is definitely not classically inspired. A series of square boxes stacked one over another is static. The term for an arrangement like this is called "dualism" and is usually to be avoided. Usually in the vertical plane designers avoid dualism in two ways. They make stack different sized rectangles one on top of another creating a heirarchy. That is the reason a chest on chest often has a square defining the bottom case and a rectangle in the upper case. In the case of graduated drawers, the Romans actually came up with this when they perfected concrete and brick construction and began making multi story buildings. To avoid dualism they graduated the stories making each floor slightly shorter than the one below. When they decorated the exterior with rows of stacked classic orders they actually continued the taper of the colunms up through each succesive floor making each about 10% shorter as it rises up. You can see this on many renaisance buildings also. I worked out a method using dividers for laying out graduated drawers that requires almost no math and is very quick to execute. I'm pretty certain that period craftsmen used a method very similar that could be accomplished with speed. Unfortunitely, its one of those things I could show you in 60 seconds but it would take about four pages to explain with text. I have a couple of writing projects in the works, so I will get something in print you can follow.
George Walker
