Drawplate armature, edge-power ratios, and an angle-sighting device
Soldering plates to the pyramid with rib and centrings; proportion of cutting powers; aligning incident and reflected rays
This sheet continues the wire-drawing die (trafila) studies with three strands of notes and several marginal instruments. A triangle figure argues that the cutting power at e n follows the ratio of the bases a b and c d, tenfold in a straight figure and a hundredfold in a circular one. Soldering notes explain how to join the plates to the pyramid with a crest or rib and fix wooden centrings so the die is not bendable, finishing the armature before it is lifted from its mould. A final diagram with glass, a hole and a circle shows how to align an incident ray c o with its reflected ray o e by sighting through the hole from the opposite side; a graduated rod with plumb bob and a claw-clamp are drawn in the margin.
On this page
Cutting power follows the ratio of the bases
The proportion from effect to effect is that from cause to cause. It follows that e n, the edge of the triangle and column, has such proportion in its powers as the bases a b and c d bear one to another, namely tenfold; in a circular figure this becomes a hundredfold.
Soldering the plates to the pyramid with rib and centrings
The passage teaches soldering the plates (lamine) to the pyramid together with the crest or rib, then fixing wooden centrings so the die is not bendable. Such armatures must be entirely finished before the die is lifted from its wall or mould.
Aligning incident and reflected rays through a hole
To direct the angle e to its purpose, take the incident line c o and the reflected line o e, using the central line n m marked at n. If the incident ray passes through the hole o and strikes the circle at d, place the eye at f on the opposite side of the circle and look toward e, and there the incident c o is aligned with the reflected o e at the point o.
Graduated rod with plumb bob and claw-clamp
The upper margin carries a vertical graduated rod hung with a plumb bob and, beside it, a claw-like clamping device, drawn without accompanying transcribed captions.