Chapter XI: Part 11

[132] Bacon plainly, from this passage, was inclined to believe that the moon, like the comets, was nothing more than illuminated vapor. The Newtonian law, however, has not only established its solidity, but its density and weight. A sufficient proof of the former is afforded by the attraction of the sea, and the moon’s motion round the earth.--_Ed._

[133] Rather the refraction; the sky or air, however, _reflects_ the blue rays of light.

[134] The polished surface of the glass causes the reflection in this case, and not the air; and a hat or other black surface put behind the window in the daytime will enable the glass to reflect distinctly for the same reason, namely, that the reflected rays are not mixed and confused with those transmitted from the other side of the window.

[135] These instances, which Bacon seems to consider as a great discovery, are nothing more than disjunctive propositions combined with dilemmas. In proposing to explain an effect, we commence with the enumeration of the different causes which seem connected with its production; then with the aid of one or more dilemmas, we eliminate each of the phenomena accidental to its composition, and conclude with attributing the effect to the residue. For instance, a certain phenomenon (_a_) is produced either by phenomenon (=B=) or phenomenon (=C=); but =C= cannot be the cause of _a_, for it is found in =D=, =E=, =F=, neither of which are connected with _a_. Then the true cause of phenomenon (_a_) must be phenomenon (=B=).

This species of reasoning is liable to several paralogisms, against which Bacon has not guarded his readers, from the very fact that he stumbled into them unwittingly himself. The two principal ones are false exclusions and defective enumerations. Bacon, in his survey of the causes which are able to concur in producing the phenomena of the tides, takes no account of the periodic melting of the Polar ice, or the expansion of water by the solar heat; nor does he fare better in his exclusions. For the attraction of the planets and the progression and retrograde motion communicated by the earth’s diurnal revolution, can plainly affect the sea together, and have a simultaneous influence on its surface.

Bacon is hardly just or consistent in his censure of Ramus; the end of whose dichotomy was only to render reasoning by dilemma, and crucial instances, more certain in their results, by reducing the divisions which composed their parts to two sets of contradictory propositions. The affirmative or negative of one would then necessarily have led to the acceptance or rejection of the other.--_Ed._

[136] Père Shenier first pointed out the spots on the sun’s disk, and by the marks which they afforded him, computed its revolution to be performed in twenty-five days and some hours.--_Ed._

[137] Rust is now well known to be a chemical combination of oxygen with the metal, and the metal when rusty acquires additional weight. His theory as to the generation of animals, is deduced from the erroneous notion of the possibility of spontaneous generation (as it was termed). See the next paragraph but one.

[138]

“Limus ut hic durescit, et hæc ut cera liquescit
Uno eodemque igni.”--Virg. Ecl. viii.

[139] See Table of Degrees, No. 38.

[140] Riccati, and all modern physicists, discover some portion of light in every body, which seems to confirm the passage in Genesis that assigns to this substance priority in creation.--_Ed._

[141] As instances of this kind, which the progress of science since the time of Bacon affords, we may cite the air-pump and the barometer, for manifesting the weight and elasticity of air: the measurement of the velocity of light, by means of the occultation of Jupiter’s satellites and the aberration of the fixed stars: the experiments in electricity and galvanism, and in the greater part of pneumatic chemistry. In all these cases scientific facts are elicited, which sense could never have revealed to us.--_Ed._

[142] The itinerant instances, as well as frontier instances, are cases in which we are enabled to trace the general law of continuity which seems to pervade all nature, and which has been aptly embodied in the sentence, “natura non agit per saltum.” The pursuit of this law into phenomena where its application is not at first sight obvious, has opened a mine of physical discovery, and led us to perceive an intimate connection between facts which at first seemed hostile to each other. For example, the transparency of gold-leaf, which permits a bluish-green light to pass through it, is a frontier instance between transparent and opaque bodies, by exhibiting a body of the glass generally regarded the most opaque in nature, as still possessed of some slight degree of transparency. It thus proves that the quality of opacity is not a contrary or antagonistic quality to that of transparency, but only its extreme lowest degree.

[143] Alluding to his theory of atoms.

[144] Observe the approximation to Newton’s theory. The same notion repeated still more clearly in the ninth motion. Newton believed that the planets might so conspire as to derange the earth’s annual revolution, and to elongate the line of the apsides and ellipsis that the earth describes in its annual revolution round the sun. In the supposition that all the planets meet on the same straight line, Venus and Mercury on one side of the sun, and the earth, moon, Mars, Jupiter and Saturn on the side diametrically opposite; then Saturn would attract Jupiter, Jupiter Mars, Mars the moon, which must in its turn attract the earth in proportion to the force with which it was drawn out of its orbit. The result of this combined action on our planet would elongate its ecliptic orbit, and so far draw it from the source of heat, as to produce an intensity of cold destructive to animal life. But this movement would immediately cease with the planetary concurrence which produced it, and the earth, like a compressed spring, bound almost as near to the sun as she had been drawn from it, the reaction of the heat on its surface being about as intense as the cold caused by the first removal was severe. The earth, until it gained its regular track, would thus alternately vibrate between each side of its orbit, with successive changes in its atmosphere, proportional to the square of the variation of its distance from the sun. In no place is Bacon’s genius more conspicuous than in these repeated guesses at truth. He would have been a strong Copernican, had not Gilbert defended the system.--_Ed._

[145] This is not true except when the projectile acquires greater velocity at every successive instant of its course, which is never the case except with falling bodies. Bacon appears to have been led into the opinion from observing that gunshots pierce many objects at a distance from which they rebound when brought within a certain proximity of contact. This apparent inconsistency, however, arises from the resistance of the parts of the object, which velocity combined with force is necessary to overcome.--_Ed._

[146] This passage shows that the pressure of the external atmosphere, which forces the water into the egg, was not in Bacon’s time understood.--_Ed._

[147] We have already alluded, in a note prefixed to the same aphorism of the first book, to Newton’s error of the absolute lightness of bodies. In speaking again of the volatile or spiritual substances (Aph. xl. b. ii.) which he supposed with the Platonists and some of the schoolmen to enter into the composition of every body, he ascribes to them a power of lessening the weight of the material coating in which he supposes them inclosed. It would appear from these passages and the text that Bacon had no idea of the relative density of bodies, and the capability which some have to diminish the specific gravity of the heavier substances by the dilation of their parts; or if he had, the reveries in which Aristotle indulged in treating of the soul, about the appetency of bodies to fly to kindred substances--flame and spirit to the sky, and solid opaque substances to the earth, must have vitiated his mind.--_Ed._

[148] Römer, a Danish astronomer, was the first to demonstrate, by connecting the irregularities of the eclipses of Jupiter’s satellites with their distances from the earth, the necessity of time for the propagation of light. The idea occurred to Dominic Cassini as well as Bacon, but both allowed the discovery to slip out of their hands.--_Ed._

[149] The author in the text confounds inertness, which is a simple indifference of bodies to action, with gravity, which is a force acting always in proportion to their density. He falls into the same error further on.--_Ed._

[150] The experiments of the last two classes of instances are considered only in relation to practice, and Bacon does not so much as mention their infinitely greater importance in the theoretical part of induction. The important law of gravitation in physical astronomy could never have been demonstrated but by such observations and experiments as assigned accurate geometrical measures to the quantities compared. It was necessary to determine with precision the demi-diameter of the earth, the velocity of falling bodies at its surface, the distance of the moon, and the speed with which she describes her orbit, before the relation could be discovered between the force which draws a stone to the ground and that which retains the moon in her sphere.

In many cases the result of a number of particular facts, or the collective instances rising out of them, can only be discovered by geometry, which so far becomes necessary to complete the work of induction. For instance, in the case of optics, when light passes from one transparent medium to another, it is refracted, and the angle which the ray of incidence makes with the superficies which bounds the two media determines that which the refracted ray makes with the same superficies. Now, all experiment can do for us in this case is, to determine for any particular angle of incidence the corresponding angle of refraction. But with respect to the general rule which in every possible case deduces one of these angles from the other, or expresses the constant and invariable relation which subsists between them, experiment gives no direct information. Geometry must, consequently, be called in, which, when a constant though unknown relation subsists between two angles, or two variable qualities of any kind, and when an indefinite number of values of those quantities are assigned, furnishes infallible means of discovering that unknown relation either accurately or by approximation. In this way it has been found, when the two media remain the same, the cosines of the above-mentioned angles have a constant ratio to each other. Hence, when the relations of the simple elements of phenomena are discovered to afford a general rule which will apply to any concrete case, the deductive method must be applied, and the elementary principles made through its agency to account for the laws of their more complex combinations. The reflection and refraction of light by the rain falling from a cloud opposite to the sun was thought, even before Newton’s day, to contain the _form_ of the rainbow. This philosopher transformed a probable conjecture into a certain fact when he deduced from the known laws of reflection and refraction the breadth of the colored arch, the diameter of the circle of which it is a part, and the relation of the latter to the place of the spectator and the sun. Doubt was at once silenced when there came out of his calculus a combination of the same laws of the simple elements of optics answering to the phenomena in nature.--_Ed._

[151] As far as this motion results from attraction and repulsion, it is only a simple consequence of the last two.--_Ed._

[152] These two cases are now resolved into the property of the capillary tubes and present only another feature of the law of attraction.--_Ed._

[153] This is one of the most useful practical methods in chemistry at the present day.

[154] See Aphorism xxv.

[155] Query?

[156] Observe this approximation to Newton’s theory.

[157] Those differences which are generated by the masses and respective distances of bodies are only differences of quantity, and not specific; consequently those three classes are only one.--_Ed._

[158] See the citing instances, Aphorism xl.

[159] Aristotle’s doctrine, that sound takes place when bodies strike the air, which the modern science of acoustics has completely established, was rejected by Bacon in a treatise upon the same subject: “The collision or thrusting of air,” he says, “which they will have to be the cause of sound, neither denotes the form nor the latent process of sound, but is a term of ignorance and of superficial contemplation.” To get out of the difficulty, he betook himself to his theory of spirits, a species of phenomena which he constantly introduces to give himself the air of explaining things he could not understand, or would not admit upon the hypothesis of his opponents.--_Ed._

[160] The motion of trepidation, as Bacon calls it, was attributed by the ancient astronomers to the eight spheres, relative to the precession of the equinoxes. Galileo was the first to observe this kind of lunar motion.--_Ed._

[161] Part of the air is expanded and escapes, and part is consumed by the flame. When condensed, therefore, by the cold application, it cannot offer sufficient resistance to the external atmosphere to prevent the liquid or flesh from being forced into the glass.

[162] Heat can now be abstracted by a very simple process, till the degree of cold be of almost any required intensity.--_Ed._

[163] It is impossible to compare a degree of heat with a degree of cold, without the assumption of some arbitrary test, to which the degrees are to be referred. In the next sentence Bacon appears to have taken the power of animal life to support heat or cold as the test, and then the comparison can only be between the degree of heat or of cold that will produce death.

The zero must be arbitrary which divides equally a certain degree of heat from a certain degree of cold.--_Ed._

[164] It may often be observed on the leaves of the lime and other trees.

[Transcriber’s Notes:

Punctuation errors were corrected.
Inconsistent hyphenation was retained.
“De la Lande” and “La Lande” both appear in text and were retained.
“Shenier”, editor’s spelling of “Scheiner”, was retained.
On p. 37, a paragraph break was inserted before "There is a clear
example ...".
On p. 44, “the” was changed from “The” (the usual method).
On p. 85, “that” was changed from “That” (that a species).
On p. 86, “that” was changed from “That” (that an instrument).
On p. 118, “aëriform” was changed from “aeriform” (aëriform or
igniform).
On p. 178, “borrow” was changed from “brorrow” (to borrow a term
from the grammarians).
On p. 204, “sufficiently” was changed from “sufficietly” (but
sufficiently dense).
On p. 219, “quantity” was changed from “quanity” (quantity of gold).
In footnote [5], “psychological” was changed from “pyschological”
(most other psychological).
In footnote [23], “that” was changed from “tha” (that we have
nothing).
In footnote [33], "72" was changed from “22” (Acad. Prior. ii. 72.).
In footnote [60], “ix.” was changed from “x.” (Livy, lib. ix.).
In footnote [71], “οὐσία” was changed from “οὐδία”.
In footnote [86], “necessary” was changed from “necesary” (necessary
to invent).
In footnote [87], “liquor” was changed from “liqour” (the liquor
rose).
In footnote [161], “the” was changed from “th” (by the flame).]