Folding wooden joints for portable tables and pavilions
Hinges that fold flat or to a right angle, beside a balance rule reading weights 8 6 4 2 1½
Folio 172r combines two subjects. At the left, three carefully shaded drawings show wooden hinge-joints: one (a b) that folds fully backward and forward with a right-angled bend, and another that folds only as far as the straight line n f m. Leonardo gives their uses — the first for the jointed walls of wooden pavilions, so they can be dismounted and carried, the second for portable tables. At the right, under the heading 'General rule,' a beam a b takes the correspondences of the weights 8, 6, 4, 2, 1½ hung below as if it were the arm of a balance, to be calculated among themselves; pulley-and-weight diagrams accompany it.
On this page
A joint that folds fully backward and forward
a b is a joint that bends entirely backward and forward, with a right-angled bend — something the lowest joint below it cannot do. The 3D drawings show the interlocking wooden knuckles.
A joint limited to the straight line n f m
This joint cannot bend beyond the straight position n f m. It is useful in portable tables, while the joint above it serves the folding walls of wooden pavilions, to make them dismountable and portable.
The arm a b as a balance for graded weights
Under the heading 'General rule,' the beam a b takes the correspondences of the weights below — 8, 6, 4, 2, 1½ — as if it were the arm of a balance, and so they are to be calculated among themselves.