9.12
The caltrops should be made of plaited yew, stripped of the bark, so as not to rot. They should have circular crowns, and the nails should be of iron and wood alternately, plaited into the rim,The rim (an unsatisfactory rendering) is the same thing as the crown. the iron nails being the longer, so that the wooden ones will yield to the foot and the others hurt it.
9.13
The noose of the cord to be laid on the crown and the cord itself should be of woven esparto,Yates (Textrinum Antiquorum) believes that the plant meant is Spanish broom (Genista). But it is indeed the grass esparto, Stipa tenacissima. since this is rot-proof. The noose itself and the cord must be strong; and the clog attached must be of common or evergreen oak, twenty-seven inches long, not stripped of the bark, and three inches thick.
9.14
To set the caltrops make a round hole in the ground fifteen inches deep, of the same size at the top as the crowns of the traps, but tapering towards the bottom. Make shallow drills in the ground for the cord and the clog to lie in.
9.15
Having done this lay the caltrop on the hole a little below the surface, and level, and put the noose of the cord round the top. Having laid the cord and the clog in their places, lay spindle-wood twigs on the top, not letting them stick out beyond the circle, and on these any light leaves in season.
9.16
Next throw some earth on them, beginning with the surface soil taken from the holes, and on top of this some unbroken soil from a distance, in order that the position may be completely concealed from the deer. Remove any earth remaining over to a place some distance from the caltrop; for if the deer smells earth recently disturbed, it shies; and it is not slow to smell it.
