“If you want to make a hole underground easily, get the instrument shown above. Then, to make the hole, turn the screw to the right using lever m n, and the screw will drive in, making of the ground a female for itself. And when it has gone in as you wish, fix lever m n. And turn lever f g to the left, in the opposite direction—indeed, it would be better to turn in the same direction—and the screw will return, pulling itself out without turning: it will carry with itself the earth that was on top of it.”
This drill can be used for excavating deep
into the earth. It is formed of an endless screw
anchored to a wooden structure with four feet.
The screw is actuated by two bars: one allows
it to turn as it descends and penetrates into
the ground, and the other raises it while holding
it steady so as to carry away the earth.
The model is based on the drawing:
- Manuscript B f. 65 r. (1487-1490)
Paris, Institut de France