Interpretation of certain words

occurring throughout this

treatise.

Terrella original: "Terrella" is a magnet adapted into a spherical shape.
Verticity, or polar vigor, original: "Verticitas, seu vigor polaris" is that turning power of the magnet toward the poles.
Excited iron original: "Ferrum excitum" is that which acquires strength from a magnet.
A steel needle original: "Obelus chalybeus" is a thin, long, and pointed piece of iron.
A cork float original: "Raticula suberea" is a small ship made of cork.
To situate or rectify instruments original: "Situare instrumenta seu rectificare" is to place them toward the 4 quarters of the world.
Variation of the magnet original: "Variatio magnetis" is nothing other than its declination from the polar line.
Chalybodeixis or chalyboklisis steel-pointing or steel-inclination signify the same thing.