INDEX OF CHAPTERS.

3. On the color of the earth, and whether it has any certain one. 120
4. On the heats and innate powers of the Earth. 124
5. That the Earth did not arise from moisture, flow, or water. 126
6. On the heights of the terrestrial globe and the mass of the waters. On the conspicuous parts, and the changes of the eminences. 129
7. That the Earth moves in a circle Gilbert was a pioneer in arguing that the Earth rotates on its axis, a radical departure from the stationary-earth model of his time.. 135
8. The Earth does not stand still in its place, nor does it derive its direction to the North and South from any system of the heavens, or any Pole of the heavens or the world, or from any gravity. 143
9. On the reason and necessity of the arrangement of poles in nature, and the imitation of parts toward that conformity. 145
10. That the motion of the globes comes from the globes themselves, not from spheres In ancient astronomy, stars and planets were thought to be carried by invisible, physical "spheres." Gilbert argues here that planets move by their own internal power.. 147
11. On the earth and its poles. 158
12. On the motion of the first mover original: "primi mobilis." In the old system, the "Prime Mover" was the outermost sphere that moved all others; Gilbert re-evaluates this concept.. 167
13. On the Moon, or the companion of the earth. 170
14. On the Moon. 173
15. On the celestial substance of the Moon. 175
16. On the face and spots of the Moon. 176
17. On the Lunar path. 178
18. On the motion of the Moon. 179
19. The Earth is within the sphere of influence of the Moon’s power, and the Moon is within the sphere of magnetic influence original: "orbem virtutis magneticæ." Gilbert famously viewed the Earth as a giant magnet whose "virtue" or power extended into space. of the earth. 186
20. A hypothesis of the motive system of the world; the visible face and adornment of the further world and the stars commonly called "fixed" by men, the distance of most of which is entirely unknown, and inaccessible by any tricks of machines or mathematical scales. 192
21. Whether the light of the Sun removes the sight of the stars during the day, or rather the earth, illuminated by the Sun, disturbs the sense of the eyes with that light. 195
22. On the motion of the Sun and the earth. 196

23. On the twinkling of the stars. 206
24. On the stars. 207
25. On light and radiance original: "de luce & lumine." In Latin physics, "lux" usually refers to the source of light, while "lumen" refers to the light filling a space.. 210
26. On twilights and light. 211
27. On effluvia effluvia: microscopic emanations or "exhalations" given off by bodies, which Gilbert believed transmitted physical forces.. 213
28. Miscellaneous notes on light and radiance. 214
29. On Heat and fire. ibid.
30. On forms and the qualities of things. 215
31. On color and its opposites. 216
32. On the generation original: "generatione." This refers to how things are created or come into being in the natural world. of things. 217
33. On the ether. 218

OF THE THIRD BOOK.

CHAPTER I.

1. What Meteorology is. Page 221
2. On the matter of higher impressions original: "impressionum." This term was used for atmospheric phenomena like clouds, rain, or shooting stars.. 222
3. On Comets. 223
4. That Comets are often above the Moon. 236
5. Against the deep-rooted superstition concerning the orbits of the Planets—which the common sort of philosophers call "heaven"—as if it were a fifth nature original: "quintam naturam." This refers to the "Quintessence," the supposed unchanging material of the heavens in Aristotelian thought. and an immutable essence, like a dwelling of the gods. 238
6. That bodies are created and changed above the path of the Moon. 242
7. That comets sometimes exist below the Moon. ibid.
8. On the Milky Way. 247
9. On clouds. 251
10. Why clouds hang in the air. 252
11. On rain. 253

OF THE FOURTH BOOK.

CHAPTER I.

1. Wind is not created by a hot and dry exhalation. Page 254
2. The origin of the motion of the winds does not happen from a higher place. 259
3. On observations of the winds. 260
4. On the qualities, distinctions, and temperatures of the winds. 261
5. On...