I am rereading it, looking especially at his use of Practical Geometry.
His first drawings, A and B, on Plate 1 are a plan and section of a drafting board. His instructions include how to construct the frame and the panel, and how to locate the small wood buttons which will keep the dampened paper in place while it dries by the fireplace to become "smooth as a drum head" .*
Drawing C is a T Square whose construction is also described.
He lists the tools a student would need; including a small compass, often called a 'bow pen'.
The rest of Plate 1, Plates 2, 3, with Biddle's descriptions explain "the most useful geometric problems every Carpenter ought to be acquainted with."*
I read between the lines: What was common knowledge that did not need explanation?
- 'Carpenter's Assistants' might have been men who needed to learn more about construction but had not had regular apprenticeships. Many apprentices ran away before completing their training; the most famous one is Benjamin Franklin.
- The carpenter's assistant had little experience with paper for architectural drawings. He used a convenient board, a compass, a straight edge, and an awl when he needs to work out a design. These designs are often found on boards during renovation.
- Biddle specified the compass to be small because there are many different sized compasses. The ones shown here are in a cabinet maker's shop. The biggest is about 16" tall
- Geometry was a practical tool in construction.
Biddle had set up a school to teach 'architecture' to carpenters. Assistants might not have been trained to draw in their apprenticeships. Those who designed might not trained under a master builder. Biddle himself was a contractor becoming an architect.
Biddle has includes 2 drawings of the same construction. Biddle first explains the design, Plate 15. Then he details how to make the construction drawing become an inviting illustration for a potential client, Plate 16.
Here is Plate 15. In his description Biddle says he gives 'the lines of a pitch pediment frontispiece'. He writes about 'Lines' as Serlio did: the Lines for layout and design. He adds that the "Column is made 10 diameters in height." The use of diameter of the column as a measurement is discussed by Palladio.
Biddle says for the best appearance "the door should be as wide as half its height"*. The scale on the right side of the drawing is labeled '10 diameters'. Did the 'door' consisted of just the part that's hinged? No, Biddle's dimensions include the door and its surround. Here is the door with a height of 10 units divided into 2 red squares, each 5 units square.
As I followed Biddle's notes and dimensions on the drawing I learned how he thought about construction and design: his unit is the door and its frame: the 'door' itself was not the measure; the door frame between the columns is. The column's height includes its base and its capital, but not the lower base which is noted as 8" high. This allows the base to be adjusted to fit the vagaries of the location.
Of course the fanlight is a semicircle. The frame is half the height of the squares of the door.
The key stone of the semicircular fanlight was the center of the square, the height of the pediment 3/4 of the square.
The roof pitch falls exactly along the Lines which cross the square and locate its 3/4 mark.
The notes on the right side about the height of the little columns in the architrave and the return of the eaves reference the span of the door which is derived from the height of the columns.
Biddle notes at the bottom of the actual door its width: 9 parts. the parts lay out the panels. The panels themselves are 3 parts wide. Their length and spacing is also determined by the 9 parts.
The fan light's rays are also set by the 9 units. . The tic marks for the 9 units extended to the arc of the fan light layout the fins. The rhythm for the main fins is 1,2,3,2,1. In the center of the 'petals' of the fan lights are more tic marks - the centers of the arcs that create the tracery.
I tried to draw this clearly. What resulted was a jumble of lines. I'll try words:
Biddle began with the diameter of the column. He used 10 diameters to create 2 squares for door and 3/4 of the square for a fanlight and architrave. His 5 unit width is divided into 10 units, 9 of which are the physical door. The Lines inform all his design.
Biddle uses 10 parts because he supposes
"that the door is for a town house with a narrow front..." The parts will be in proportion to each other, but take up less space.
The square shown here has already been divided into 4 equal parts. The Lines divide the 4 rectangles into 5 rectangles. The bottom and top lines defining the square are thus divided into 5 equal parts.
Here is the same entrance shaded. He writes " ...the student should make it his business to understand the effects of light and shade..." He explains how to think about shading in 2 paragraphs, where "the shade should be strong", where the part should be "bright".
Plates 17 and 18 are similar: one drawing setting up the design itself, the next explaining how to shade the design.
* Plates 1, 2, 3, 15, and 16, and their descriptions
Owen Biddle, The Young Carpenter's Assistant; or, A System of Architecture Adapted to the Style of Building in the United States, 1805, Benjamin Johnson, Philadelphia, and Ronalds & London, New York. Reprint 2006, Dover Publications, Inc.
2 good biographies of Biddle: 1) the introduction to the Dover Edition of Biddle book by Bryan Clark Green. 2) an article by Micheal J. Lewis in American Architects and Their Books to 1848, edited by Hafertepe and O'Gorman, 2001, U.Mass Press.