sciences, every step of the way, as it leaves some things behind, also gives us a nearer prospect of those that remain: and as we report this particular topical invention deficient, we think proper to give an example of it in the subject of gravity and levity. 1. Let inquiries be made what kind of bodies are susceptible of the motion of gravity; what of levity; and if there be any of a middle or neutral nature. 2. After the simple inquiry of gravity and levity, proceed to a comparative inquiry; viz., which heavy bodies weigh more, and which less, in the same dimensions; and of like ones, which mount upward the swifter, and which the slower. 3. Inquire what effect the quantity of the body has in the motion of gravity. This at first sight may appear a needless inquiry, because motion may seem proportionable to quantity; but the case is otherwise. For although in scales quantity is equal to the gravity, yet where there is a small resistance, as in the falling of bodies through the air, quantity has but little force to quicken the descent; but twenty pounds of lead, and a single pound, fall nearly in the same time. 4. Inquire whether the quantity of a body may be so increased as that the motion of gravity shall be entirely lost, as in the globe of the earth, which hangs pendulous without falling. Query, therefore, whether other masses may be so large as to sustain themselves? For that bodies should move to the centre of the earth is a fiction; and every mass of matter has an aversion to local motion, till this be overcome by some stronger impulse. 5. Inquire into the effects and nature of resisting mediums, as to their influencing the motion of gravity; for a falling body either penetrates and cuts through the body it meets in its way, or else is stopped by it. If it pass through, there is a penetration, either with a small resistance, as in air, or with a greater, as in water. If it be stopped, it is stopped by an unequal resistance, where there is a preponderancy, as when wood is laid upon wax; or by an equal resistance, as when water is laid upon water, or wood upon wood of the same kind; which is what the schools pretend, when they idly imagine that bodies do not gravitate in their own places. And all these circumstances alter the motion of gravity; for heavy bodies move after one way in the balance, and after another in falling: and, which may seem strange, after one way in a balance suspended in the air, and after another in a balance plunged in water; after one way in falling through water, and after another when floating upon it. 6. Inquire into the effects of the figure of the descending body, in directing the motion of gravity: suppose of a figure broad and thin, cubical, oblong, round, pyramidal, etc.; and how bodies turn themselves while they remain in the same position as when first let go. 7. Inquire into the effects of the continuation and progression of the fall or descent itself, as to the acquiring a greater impulse or velocity, and in what proportion and to what length this velocity is increased; for the ancients, upon slender consideration, imagined that this motion, being natural, was always upon the increase. 8. Inquire into the effects of distance, or the near approach of a body descending to the earth, so as to fall swifter, slower, or not at all, supposing it were to be out of the earth's sphere of activity, according to Gilbert's opinion; as also the effects of plunging the falling body deeper into the earth, or placing it nearer the surface; for this also varies the motion, as is manifest to those who work in mines. 9. Inquire into the effects of the difference of bodies, through which the motion of gravity is diffused and communicated; and whether it is equally communicated through soft and porous bodies, as through hard and solid ones. Thus if the beam of a scale were one half of wood, and the other half of silver, yet of the same weight; inquire whether this would not make an alteration in the scales: and again, whether metal laid upon wool, or a blown bladder, would weigh the same as in the naked scale. 10. Inquire into the effects of the distance of a body from the point of suspension in the communication of the motion of gravity; that is, into the earlier or later perception of its inclination or depression: as in scales, where one side of the beam is longer, though of the same weight with the other, whether this inclines the beam; or in siphons, where the longer leg will draw the water, though the shorter, being made wider, contains a greater weight of water. 11. Inquire into the effects of intermixing or coupling a light body and a heavy one, for lessening the gravity of bodies; as in the weight of creatures alive and dead. 12. Inquire into the ascents and descents of the lighter and heavier parts of one entire body: whence curious separations are often made, as in the separation of wine and water, the rising of cream from milk, etc. 13. Inquire what is the line and direction of the motion of gravity, and how far it respects the earth's centre, that is, the mass of the earth; or the centre of its own body, that is, the appetite of its parts. For these centres are properly supposed in demonstrations, but are otherwise unserviceable in nature. 14. Inquire into the comparative motion of gravity, with other motions, or to what motions it yields, and what it exceeds. Thus in the motion they call violent, the motion of gravity is withheld for a time; and so when a large weight of iron is raised by a little loadstone, the motion of gravity gives way to the motion of sympathy. 15. Inquire concerning the motion of the air, whether it rises upward, or be as it were neutral, which is not easy to be discovered without some accurate experiments; for the rising up of air at the bottom of water, rather proceeds from a resistance of the water, than the motion of the air, since the same also happens in wood. But air mixed with air makes no discovery; for air in air may seem as light, as water in water seems heavy: but in bubbles, which are air surrounded with a thin pellicle of water, it stands still for a time. 16. Let the bounds of levity be inquired after; for though men make the centre of the earth the centre of. gravity, they will perhaps hardly make the ultimate convexity of the heavens the boundary of levity; but rather, perhaps, as heavy bodies seem to be carried so far, that they rest, and grow as it were immovable; light bodies are carried so far, that they begin a rotation or circular motion. 17. Inquire the cause why vapors and effluvia are carried so high as that called the middle region of the air, since the matter of them is somewhat gross, and the rays of the sun cease alternately by night. 18. Inquire into the tendency of flame upward, which is the more abstruse, because flame perishes every moment, unless perhaps in the midst of larger flames; for flames broken from their continuity are of small duration. 19. Inquire into the motion and activity of heat upward; as when heat in ignited iron sooner creeps upward than downward. And thus much by way of example of our particular topical inquiry. We must, for a conclusion, admonish mankind to alter their particular topics in such manner, as after some considerable progress made in the inquiry, to raise topic after topic, if they desire to ascend to the pinnacle of the sciences. For my own part, I attribute so much to these particular topics, that I design a particular work upon their use, in the more eminent and obscure subjects of nature; for we are masters of questions, though not of things. And here we close the subject of invention. CHAPTER IV The Art of Judgment divided into Induction and the Syllogism. Induction developed in the Novum Organum. The Syllogism divided into Direct and Inverse Reduction. Inverse Reduction divided into the Doctrine of Analytics and Confutations. The division of the latter into Confutations of Sophisms, the Unmasking of Vulgarisms (Equivocal Terms), and the Destruction of Delusive Images or Idols. Delusive Appearances divided into Idola Tribûs, Idola Specûs, and Idola Fori. Appendix to the Art of Judgment. The Adapting the Demonstration to the Nature of the Subject W E COME now to the art of judgment, which treats of the nature of proof or demonstration. This art, as it is commonly received, concludes either by induction or syllogism: for enthymemes and examples are only abridgments of these two.' As to judgment by induction, we need not be large upon it, because what is sought we both find and judge of, by the same operation of the mind. Nor is the matter here transacted by a medium, but directly almost in the same manner as by the sense; for sense, in its primary objects, at once seizes the image of the object, and assents to the truth of it. It is otherwise in syllogism, whose proof is not direct, but mediate; and, therefore, the invention of the medium is one thing, and judgment, as to the consequence of an argument, another: for the mind first casts about, and afterward acquiesces. But for the corrupt form of induction, we entirely ignore it, and refer the genuine one to our method of interpreting nature. And thus much of judgment by induction. The other by syllogism is worn by the file of many 1 An enthymeme is no other than a syllogism of two propositions, the third being supplied by the mind, as the word itself imports.-Ed. |