I've found another reason for Asher Benjamin's geometry lessons and the proportion diagrams on his plates.
It turns out that in 1800, the various and different measuring systems used in the western world were quite divergent. A cubit seems to have been standard measured: from your outstretched middle finger to your elbow (about 18"). But a yard might be from your finger to your nose, (36") or to your near or opposite shoulder, (30", and 42" respectively).
I think this is great, since I have been measuring with body dimensions for years - using my own body to discretely measure an interesting space without drawing attention to myself by whipping out a tape measure, or helping a client to tell me how big is 'big' by stretching out both arms and saying, "This big?"
In 1793, Napoleon tried to create a standard, a metric system, with some success. And in 1824, the English made a standard yard, also with some success. The process took a good 50 years to take hold, and today we still have lots of regional variations, not to speak of the gulf between inches and centimeters.
Here in the States people measured cloth, grain, lumber using the system they had learned in the 'old country'. A Pennsylvania carpenter who repairs 18th century houses has told me he can tell a house built by a German from one built by a Quaker by its dimensioning.
Wednesday, March 11, 2009
Tuesday, March 3, 2009
How did carpenters measure in 1797?
What does Asher Benjamin assume his readers know when he writes his first pattern book?
Instructions today for building a simple bookcase - for example - assumes the carpenter will use a tape measure and a steel carpenter's square.
By comparison, in 1797, a carpenter had a square and perhaps a folding rule.
He also had dividers and a compass. He used both to determine dimensions.
Here are Asher Benjamin's instructions for the moldings around a door (at the end of the descriptions for Plate 1). Click the picture to enlarge it - for easier reading!
The reader would have used his compass and dividers to layout the geometry, to divide a door or window width into 7 or 8 parts.
When Asher Benjamin writes his books, we were still making the parts for a house specifically for that house - no buying off the shelf.
When it came to finish work, each molding added at a door opening or chair rail was made to order, regardless of how it was measured.
Uniform measurements for construction were not necessary until people wanted interchangeable parts. If your yard was 36" and mine was 35" it didn't matter.
Benjamin's introduction to geometry - his first plates - and his descriptions of how to draw the profiles of various moldings show his readers to how adapt his patterns to their specific buildings.
The Country Builder's Assistant, by Asher Benjamin, 1797, shown above, is a reprint by Applewood Books, Bedford, Massachusetts, 1992. The originals, (worn. well used and well loved!) are often available in rare book libraries.