XI

The investigation of forms proceeds thus: a nature being given, we must first of all have a muster or presentation before the understanding of all known instances which agree in the same nature, though in substances the most unlike. And such collection must be made in the manner of a history, without premature speculation, or any great amount of subtlety. For example, let the investigation be into the form of heat.

Instances Agreeing in the Nature of Heat

1. The rays of the sun, especially in summer and at noon.

2. The rays of the sun reflected and condensed, as between mountains, or on walls, and most of all in burning glasses and mirrors.

3. Fiery meteors.

4. Burning thunderbolts.

5. Eruptions of flame from the cavities of mountains.

6. All flame.

7. Ignited solids.

8. Natural warm baths.

9. Liquids boiling or heated.

10. Hot vapors and fumes, and the air itself, which conceives the most powerful and glowing heat if confined, as in reverbatory furnaces.

11. Certain seasons that are fine and cloudless by the constitution of the air itself, without regard to the time of year.

12. Air confined and underground in some caverns, especially in winter.

13. All villous substances, as wool, skins of animals, and down of birds, have heat.

14. All bodies, whether solid or liquid, whether dense or rare (as the air itself is), held for a time near the fire.

15. Sparks struck from flint and steel by strong percussion.

16. All bodies rubbed violently, as stone, wood, cloth, etc., insomuch that poles and axles of wheels sometimes catch fire; and the way they kindled fire in the West Indies was by attrition.

17. Green and moist vegetables confined and bruised together, as roses packed in baskets; insomuch that hay, if damp, when stacked, often catches fire.

18. Quicklime sprinkled with water.

19. Iron, when first dissolved by strong waters in glass, and that without being put near the fire. And in like manner tin, etc., but not with equal intensity.

20. Animals, especially and at all times internally; though in insects the heat is not perceptible to the touch by reason of the smallness of their size.

21. Horse dung and like excrements of animals, when fresh.

22. Strong oil of sulphur and of vitriol has the effect of heat in burning linen.

23. Oil of marjoram and similar oils have the effect of heat in burning the bones of the teeth.

24. Strong and well rectified spirit of wine has the effect of heat, insomuch that the white of an egg being put into it hardens and whitens almost as if it were boiled, and bread thrown in becomes dry and crusted like toast.

25. Aromatic and hot herbs, as dracunculus, nasturtium vetus, etc., although not warm to the hand (either whole or in powder), yet to the tongue and palate, being a little masticated, they feel hot and burning.

26. Strong vinegar, and all acids, on all parts of the body where there is no epidermis, as the eye, tongue, or on any part when wounded and laid bare of the skin, produce a pain but little differing from that which is created by heat.

27. Even keen and intense cold produces a kind of sensation of burning: "Nec Boreæ penetrabile frigus adurit." ¹

28. Other instances.

This table I call the Table of Essence and Presence.