HKB
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Often appears with: experiment, observation, and evidence · logic, method, and demonstration · fate, destiny, and necessity · perception and the senses · reason and the intellect · weather, storms, and the seasons · the earth and its formation · strata, rocks, and the geological record · volcanoes, earthquakes, and catastrophe · the nature and attributes of God · the human body and its parts · medicine, disease, and healing
Usually: argument (558) · curiosity (416) · detachment (224) · skepticism (208) · commentary or gloss (76) · narrative (67) · reflection (57) · wonder (41) · censure (29) · crisis of belief (23)
“A defect in any of these particulars destroys the form; and the matter of which it is composed is again set loose, and is thrown into irregular motions and fermentations, till it unite itself to some other regular form.” David Hume, Dialogues Concerning Natural Religion · observation
“The law of the conservation of the mass of a system becomes identical with the law of the conservation of energy, and is only valid provided that the system neither takes up nor sends out energy.” Albert Einstein, Relativity: The Special and General Theory · insight
“Bodies which are moving under the sole influence of a gravitational field receive an acceleration, which does not in the least depend either on the material or on the physical state of the body.” Albert Einstein, Relativity: The Special and General Theory · insight
“Guided by this example, we see that our extension of the principle of relativity implies the necessity of the law of the equality of inertial and gravitational mass.” Albert Einstein, Relativity: The Special and General Theory · precept
“From this we conclude, that, in general, rays of light are propagated curvilinearly in gravitational fields.” Albert Einstein, Relativity: The Special and General Theory · insight
“Electrostatics is contained in electrodynamics as a limiting case; the laws of the latter lead directly to those of the former for the case in which the fields are invariable with regard to time.” Albert Einstein, Relativity: The Special and General Theory · observation
“In gravitational fields there are no such things as rigid bodies with Euclidean properties; thus the fictitious rigid body of reference is of no avail in the general theory of relativity.” Albert Einstein, Relativity: The Special and General Theory · insight
“On the basis of the general theory of relativity, it is found that the ellipse of every planet round the sun must necessarily rotate in the manner indicated above; that for all the planets, with the exception of Mercury, this rotation is too small to be detected with the delicacy of observation possible at the present time; but that in the case of Mercury it must amount to 43 seconds of arc per century, a result which is strictly in agreement with observation.” Albert Einstein, Relativity: The Special and General Theory · observation
“the great charm resulting from this consideration lies in the recognition of the fact that the universe of these beings is finite and yet has no limits.” Albert Einstein, Relativity: The Special and General Theory · insight
“Undaunted by the [first world] war and by difficulties of both a material and a psychological nature aroused by the war, these societies equipped two expeditions—to Sobral (Brazil), and to the island of Principe (West Africa)—and sent several of Britain’s most celebrated astronomers in order to obtain photographs of the solar eclipse of 29th May, 1919.” Albert Einstein, Relativity: The Special and General Theory · observation
“There does arise, however, a strange difficulty. The interpretation of the galactic line-shift discovered by Hubble as an expansion (which can hardly be doubted from a theoretical point of view), leads to an origin of this expansion which lies “only” about 109 years ago, while physical astronomy makes it appear likely that the development of individual stars and systems of stars takes considerably longer.” Albert Einstein, Relativity: The Special and General Theory · observation
“We are now in a position to formulate more exactly the idea of Minkowski, which was only vaguely indicated in Section XVII.” Albert Einstein, Relativity: The Special and General Theory · observation
Darwin explains geology’s imperfect fossil record, proposes using rates of organic change between formations as a rough measure of time, and argues that “secondary causes” rather than catastrophes produce species turnover.
sides of a continent, and the nature of the various inhabitants of that continent in relation to their apparent means of immigration, some light can be thrown on ancient geography. The noble science of Geology loses glory from the extreme imperfection of the record. The crust of the earth with its embedded remains must not be looked at as a well-filled museum, but as a poor collection made at hazard and at rare inte…
He challenges the idea that industrial schools alone can uplift Black Americans, warning against treating people as material resources for profit, and insisting that education should also pursue culture and character.
brought it in direct touch with the South’s magnificent industrial development, and given an emphasis which reminded black folk that before the Temple of Knowledge swing the Gates of Toil. Yet after all they are but gates, and when turning our eyes from the temporary and the contingent in the Negro problem to the broader question of the permanent uplifting and civilization of black men in America, we have a right to…
During the Arctic voyage Equiano’s journal-writing nearly burns him to death in a combustible cabin, then he distills fresh water, reaches Greenland latitudes, and records ice, whales, sea-horses, and bears.
but at last, not being able to write my journal in any other part of the ship, I was tempted again to venture by stealth with a light in the same cabin, though not without considerable fear and dread on my mind. On the 20th of June we began to use Dr. Irving's apparatus for making salt water fresh; I used to attend the distillery: I frequently purified from twenty-six to forty gallons a day. The water thus distilled …
He argues against ideas of plague as purely an immediate act from Heaven or purely insect-carried air, describing contagion via “effluvia,” and criticizes civic negligence and under-preparation as deadly.
the bearers been obliged to go in to fetch out the dead bodies, not being able to bring them to the door, and at last none left to do it. (3) This put it out of question to me, that the calamity was spread by infection; that is to say, by some certain steams or fumes, which the physicians call effluvia, by the breath, or by the sweat, or by the stench of the sores of the sick persons, or some…
Du Bois reflects on teaching at Atlanta University and the moral dishonesty forced by segregation, describing the anxious classroom gaze of youth and pivoting to how he teaches history and economics through concrete social problems.
of hell or some pulse of high heaven may suddenly flash. Ah! That mighty pause before the class,--that orison and benediction--how much of my life it has been and made. I fought earnestly against posing before my class. I tried to be natural and honest and frank, but it was a bitter hard. What would you say to a soft, brown face, aureoled in a thousand ripples of gray-black hair, which knells suddenly: "Do you trust…
Plutarch opens the Timoleon biography by explaining that writing lives of great men improves his own morals, then sets out Syracuse’s crisis before Timoleon’s mission and the rise of tyrannical Dionysius.
TIMOLEON It was for the sake of others that I first commenced writing biographies; but I find myself proceeding and attaching myself to it for my own; the virtues of these great men serving me as a sort of looking-glass, in which I may see how to adjust and adorn my own life. Indeed, it can be compared to nothing but daily living and associating together; we receive, as it were, in our inquiry, and entertain each s…
At Ecbatana and Babylon, Alexander witnesses naphtha fire and a near-fatal burning experiment, digresses on naphtha and hot soils, then records treasures at Susa and Persian kings’ stored Nile and Danube waters.
at Salamis, with a vessel set forth at his own charge. So affectionate was Alexander to all kind of virtue, and so desirous to preserve the memory of laudable actions. From hence he marched through the province of Babylon, which immediately submitted to him, and in Ecbatana was much surprised at the sight of the place where fire issues in a continuous stream, like a spring of water, out of a cleft in the earth, and …
Kant presents a supposed defender of “transcendental physiocracy” (nature’s sufficiency) and argues that denying a free faculty would undermine nature’s stable lawfulness.
ON THE ANTITHESIS. The assertor of the all-sufficiency of nature in regard to causality (transcendental Physiocracy), in opposition to the doctrine of freedom, would defend his view of the question somewhat in the following manner. He would say, in answer to the sophistical arguments of the opposite party: If you do not accept a mathematical first, in relation to time, you have no need to seek a dynamical first, in …
During provision gathering under truce, Clearchus supervises engineering over trenches and water conduits with quick discipline; the army eats local palm wine, dates, and “brain” with its headache effect.
(1) I.e. the cabbage-like crown. In these villages they remained three days, and a deputation from the 17 great king arrived--Tissaphernes and the king's brother-in-law and three other Persians--with a retinue of many slaves. As soon as the generals of the Hellenes had presented themselves, Tissaphernes opened the proceedings with the following speech, through the lips of an interpreter: "Men of Hellas, I am your …
Freud lists sources of infantile sexual excitement—including temperature sensitivity, mechanical rocking, muscular fighting, fear and horror, and intellectual work—and concludes that sexual excitement follows both sensory stimulation and internal processes.
to very distinct erogenous action. Among these we will above all mention the temperature sensitiveness; this will perhaps prepare us for the understanding of the therapeutic effects of warm baths. *Mechanical Excitation.*--We must, moreover, describe here the production of sexual excitation by means of rhythmic mechanical shaking of the body. There are three kinds of exciting influences: those acting on the sensory …
Bunyan defends his writing style as fit for truth, saying metaphor can carry spiritual meaning safely, like nature’s mixed light and how fisherman and fowler use varied tactics to catch what must be sought.
wilt not read, let it alone; Some love the meat, some love to pick the bone. Yea, that I might them better palliate, I did too with them thus expostulate:-- {4} May I not write in such a style as this? In such a method, too, and yet not miss My end--thy good? Why may it not be done? Dark clouds bring waters, when the bright bring none. Yea, dark or bright, if they their silver drops Cause to descend, the e…
Darwin describes green bioluminescence and detailed flash behavior of Lampyridae fireflies and related luminous insects, including larval feeding and tail structures that produce drops of fluid.
not unpleasant. Every evening after dark this great concert commenced; and often have I sat listening to it, until my attention has been drawn away by some curious passing insect. At these times the fireflies are seen flitting about from hedge to hedge. On a dark night the light can be seen at about two hundred paces distant. It is remarkable that in all the different kinds of glowworms, shining elaters, and vario…
Darwin describes hunting wasps that paralyze spiders and stuff clay cells for larvae, then recounts a deadly contest between a Pepsis wasp and a Lycosa spider interrupted by his intervention.
might have avoided the stone, and this doubtless would have happened, if it had been originally there: but having been attacked, the lion-hearted little warriors scorned the idea of yielding. Certain wasp-like insects, which construct in the corners of the verandahs clay cells for their larvae, are very numerous in the neighbourhood of Rio. These cells they stuff full of half-dead spiders and caterpillars, which th…
Darwin continues the wasp-spider account with his interruption, then broadens to how spiders build webs, kill prey with poison, and react to disturbance in multiple specialized ways.
side of its thorax. At last, carefully examining with its antennae the now motionless spider, it proceeded to drag away the body. But I stopped both tyrant and prey. [9] The number of spiders, in proportion to other insects, is here compared with England very much larger; perhaps more so than with any other division of the articulate animals. The variety of species among the jumping spiders appears almost infinite. …
Darwin describes the tucutuco, a subterranean rodent near the Rio Parana, noting its burrows, mole-like digging, nocturnal feeding on roots, characteristic grunt, and unusual patterns of blindness and limited locomotion.
skins are of trifling value, and the meat is very indifferent. On the islands in the Rio Parana they are exceedingly abundant, and afford the ordinary prey to the Jaguar. The Tucutuco (Ctenomys Brasiliensis) is a curious small animal, which may be briefly described as a Gnawer, with the habits of a mole. It is extremely numerous in some parts of the country, but it is difficult to be procured, and never, I believe,…
Darwin discusses salt incrustations near Bahia Blanca, explaining how sulphate of soda and common salt concentrate through evaporation and speculating about how salts form via plants and black organic mud.
cannot imagine: at the same time, I must confess that my guide did not suffer at all, and was astonished that one day's deprivation should be so troublesome to me. I have several times alluded to the surface of the ground being incrusted with salt. This phenomenon is quite different from that of the salinas, and more extraordinary. In many parts of South America, wherever the climate is moderately dry, these incrus…
Darwin discusses sparse life in deep water far offshore, limited catches near Cape Horn despite abundant whales and seabirds, and then describes mysteries of how pelagic organisms subsist based on infusoria and food chains.
animal lives in the open sea, and probably wants a place of rest, I suppose this beautiful and most anomalous structure is adapted to take hold of floating marine animals. In deep water, far from the land, the number of living creatures is extremely small: south of the latitude 35 degs., I never succeeded in catching anything besides some beroe, and a few species of minute entomostracous crustacea. In shoaler water,…
Around April 26 Darwin observes basaltic lava platforms blocking the Santa Cruz for 28 miles, argues rivers cannot transport such blocks, and proposes an ancient strait whose tides eroded the basalt.
in the Santa Cruz, and that no still reaches occur in any part, this example is a most striking one, of the inefficiency of rivers in transporting even moderately-sized fragments. The basalt is only lava, which has flowed beneath the sea; but the eruptions must have been on the grandest scale. At the point where we first met this formation it was 120 feet in thickness; following up the river course, the surface imp…
Darwin proposes glacier descent depends on a low snow-line near the coast, describes ice-filled valleys and glacier falls causing waves, and speculates on earthquakes triggering disruptive glacier mass movements.
an arborescent grass, very like a bamboo, in 40 degs.; and another closely allied kind, of great length, but not erect, flourishes even as far south as 45 degs. S. An equable climate, evidently due to the large area of sea compared with the land, seems to extend over the greater part of the southern hemisphere; and, as a consequence, the vegetation partakes of a semi-tropical character. Tree-ferns thrive luxuriantl…
On March 22-23 Darwin climbs the Portillo near its crest, describes perpetual snow, cloud and moonlit effects, transparency and dryness at altitude, lightning-like electrical effects, and a descent into cloud before reaching Los Arenales.
gathering rain-storms: we may imagine that the wind, which coming from the eastward is thus banked up by the line of mountains, would become stagnant and irregular in its movements. Having crossed the Peuquenes, we descended into a mountainous country, intermediate between the two main ranges, and then took up our quarters for the night. We were now in the republic of Mendoza. The elevation was probably not under …
Einstein uses Maxwell electrodynamics and energy conservation to argue that when a body absorbs radiation energy E0 without changing its velocity, its inertial mass increases by E0/c^2, yielding E=mc^2.
or, briefly, relative to every “Galileian” system of co-ordinates. In contrast to classical mechanics; the Lorentz transformation is the deciding factor in the transition from one such system to another. By means of comparatively simple considerations we are led to draw the following conclusion from these premises, in conjunction with the fundamental equations of the electrodynamics of Maxwell: A body moving with th…
Einstein reframes gravity as a field analogous to electromagnetic fields, stating that free fall acceleration depends only on the gravitational field and not on the body’s material or physical state.
be theoretically represented much more satisfactorily than without it, and this applies particularly to the transmission of electromagnetic waves. The effects of gravitation also are regarded in an analogous manner. The action of the earth on the stone takes place indirectly. The earth produces in its surrounding a gravitational field, which acts on the stone and produces its motion of fall. As we know from experien…
Using an accelerated chest containing an observer, Einstein shows the observer can interpret effects as coming from a constant gravitational field, supporting extending relativity to accelerated frames.
this observer. He must fasten himself with strings to the floor, otherwise the slightest impact against the floor will cause him to rise slowly towards the ceiling of the room. To the middle of the lid of the chest is fixed externally a hook with rope attached, and now a “being” (what kind of a being is immaterial to us) begins pulling at this with a constant force. The chest together with the observer then begin to…
Einstein clarifies that the chest argument requires equality of inertial and gravitational mass, compares interpretations of rope tension from a free-falling versus accelerated observer, and warns that not all gravitational fields can be transformed away.
the bodies around him on the supposition of a gravitational field, and he would not be justified on the grounds of experience in supposing his reference-body to be “at rest.” Suppose that the man in the chest fixes a rope to the inner side of the lid, and that he attaches a body to the free end of the rope. The result of this will be to stretch the rope so that it will hang “vertically” downwards. If we ask for an o…
Using the equivalence principle, Einstein derives that light rays curve in gravitational fields, estimates the solar-bending angle, links this to the 1919 eclipse test, and limits the special theory’s validity to ignoring gravity.
A FEW INFERENCES FROM THE GENERAL PRINCIPLE OF RELATIVITY The considerations of Section XX show that the general principle of relativity puts us in a position to derive properties of the gravitational field in a purely theoretical manner. Let us suppose, for instance, that we know the space-time “course” for any natural process whatsoever, as regards the manner in which it takes place in the Galileian domain relativ…
Einstein continues that the general theory must obey for all gravitational fields produced by non-inertial reference bodies, discusses the need to extend ideas of space-time, and sets up the next step.
the Royal and Royal Astronomical Societies, the existence of the deflection of light demanded by theory was first confirmed during the solar eclipse of 29th May, 1919. (Cf. Appendix III.) In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of…
Einstein explains, via a uniformly rotating disc, that clocks and measuring-rods behave differently in different positions, making exact definitions of time, simultaneity, and Euclidean geometry fail in gravitational fields.
[17] This follows from a generalisation of the discussion in Section XX. XXIII. BEHAVIOUR OF CLOCKS AND MEASURING-RODS ON A ROTATING BODY OF REFERENCE Hitherto I have purposely refrained from speaking about the physical interpretation of space- and time-data in the case of the general theory of relativity. As a consequence, I am guilty of a certain slovenliness of treatment, which, as we know from the special theo…
Einstein introduces the construction of Gaussian coordinates on a continuum by using dense, non-intersecting u- and v-curves, defining “distance” with a metric-like formula.
EUCLIDEAN AND NON-EUCLIDEAN CONTINUUM The surface of a marble table is spread out in front of me. I can get from any one point on this table to any other point by passing continuously from one point to a “neighbouring” one, and repeating this process a (large) number of times, or, in other words, by going from point to point without executing “jumps.” I am sure the reader will appreciate with sufficient clearness wh…
Einstein argues that in general relativity, because light speed depends on coordinates in gravitational fields, the space-time continuum is not Euclidean and must instead be described using arbitrary Gauss coordinates without direct physical meaning.
image033 According to Gauss, this combined analytical and geometrical mode of handling the problem can be arrived at in the following way. We imagine a system of arbitrary curves (see Fig. 4) drawn on the surface of the table. These we designate as *u*-curves, and we indicate each of them by means of a number. The Curves *u* = 1, *u* = 2 and *u* = 3 are drawn in the diagram. Between the curves *u* = 1 and *u* = 2 we…
Einstein states that in special relativity the space-time interval ds^2 is preserved across all Galilean reference bodies under Lorentz transformations, and he extends this invariant “distance” to a four-dimensional continuum that can be treated like Euclidean space using an imaginary time coordinate.
*ds*2 = *dx*12 + *dx*22 + *dx*32 + *dx*42. In this case relations hold in the four-dimensional continuum which are analogous to those holding in our three-dimensional measurements. However, the Gauss treatment for *ds*2 which we have given above is not always possible. It is only possible when sufficiently small regions of the continuum under consideration may be regarded as Euclidean continua. For example, this ob…
Einstein argues that in general relativity the space-time continuum cannot generally be treated as Euclidean, so coordinates are assigned using Gauss coordinates without direct physical meaning, and he derives the Lorentz transformation by requiring light propagation in vacuo to keep the same form in different inertial systems.
*ds*2 = *dx*12 + *dx*22 + *dx*32 + *dx*42. is independent of the choice of the body of reference. We call the magnitude *ds* the “distance” apart of the two events or four-dimensional points. Thus, if we choose as time-variable the imaginary variable image035 instead of the real quantity *t*, we can regard the space-time contintium—accordance with the special theory of relativity—as a “Euclidean” four-dimensional…
Einstein describes how the general principle replaces Lorentz-transform equivalence with invariance under arbitrary substitutions of Gaussian variables, and argues that non-rigid reference bodies with clocks define time in gravitational fields.
The following statement corresponds to the fundamental idea of the general principle of relativity: “_All Gaussian co-ordinate systems are essentially equivalent for the formulation of the general laws of nature._” We can state this general principle of relativity in still another form, which renders it yet more clearly intelligible than it is when in the form of the natural extension of the special principle of rel…
He outlines a method for deriving gravitational dynamics: start in a gravity-free Galilean domain, transform to a chosen Gaussian system where a gravitational field appears, then impose energy conservation and relativity to generalize to the true gravitational law.
THE SOLUTION OF THE PROBLEM OF GRAVITATION ON THE BASIS OF THE GENERAL PRINCIPLE OF RELATIVITY If the reader has followed all our previous considerations, he will have no further difficulty in understanding the methods leading to the solution of the problem of gravitation. We start off on a consideration of a Galileian domain, *i.e.* a domain in which there is no gravitational field relative to the Galileian refere…
Einstein argues that for weak fields the theory reproduces Newtonian gravity, but he explains Mercury’s perihelion precession as a relativistic effect consistent with observation, unlike classical mechanics.
interpreting the empirical law of the equality of inertial and gravitational mass; but it has also already explained a result of observation in astronomy, against which classical mechanics is powerless. If we confine the application of the theory to the case where the gravitational fields can be regarded as being weak, and in which all masses move with respect to the coordinate system with velocities which are small…
Einstein contrasts Newton’s prediction of a star-density maximum at a center with a universe of roughly uniform density, criticizes the resulting “finite island” cosmos, and discusses Seeliger’s proposed modification of Newton’s law.
XXX. COSMOLOGICAL DIFFICULTIES OF NEWTON’S THEORY the universe is infinite. There are stars everywhere, so that the density of matter, although very variable in detail, is nevertheless on the average everywhere the same. In other words: However far we might travel through space, we should find everywhere an attenuated swarm of fixed stars of approrimately the same kind and density. This view is not in harmony with…
Using analogies of beings on a plane versus a sphere, Einstein explains how a universe can be finite yet unbounded, and extends the idea to spherical and elliptical three-dimensional spaces.
or with experience (Riemann, Helmholtz). These questions have already been treated in detail and with unsurpassable lucidity by Helmholtz and Poincaré, whereas I can only touch on them briefly here. In the first place, we imagine an existence in two dimensional space. Flat beings with flat implements, and in particular flat rigid measuring-rods, are free to move in a *plane*. For them nothing exists outside of this …
He argues that general relativity can decide whether the universe is infinite or finite, proposing a quasi-spherical, finite universe whose curvature is determined by the average matter density.
a spherical “world” and not on a Euclidean plane, for a small part of a spherical surface differs only slightly from a piece of a plane of the same size. Thus if the spherical surface beings are living on a planet of which the solar system occupies only a negligibly small part of the spherical universe, they have no means of determining whether they are living in a finite or in an infinite universe, because the “pie…
In Appendix I, Einstein derives the Lorentz transformation from light-signal propagation, relativity of measuring rods, and snapshots, first for events along the x-axis and then generally for arbitrary directions.
curved space in which the two “counter-points” are identical (indistinguishable from each other). An elliptical universe can thus be considered to some extent as a curved universe possessing central symmetry. It follows from what has been said, that closed spaces without limits are conceivable. From amongst these, the spherical space (and the elliptical) excels in its simplicity, since all points on it are equivalen…
Appendix II introduces Minkowski’s four-dimensional world by replacing real time with an imaginary time coordinate, showing that the transformation preserves a four-dimensional invariant involving space and time.
(SUPPLEMENTARY TO SECTION XI) For the relative orientation of the co-ordinate systems indicated in Fig. 2, the *x*-axes of both systems permanently coincide. In the present case we can divide the problem into parts by considering first only events which are localised on the *x*-axis. Any such event is represented with respect to the co-ordinate system *K* by the abscissa *x* and the time *t*, and with respect to the…
Einstein explains that by redefining time as an imaginary coordinate the Lorentz transformation can be characterized as an invariant four-dimensional Euclidean-like equation, making the time coordinate enter natural laws like the three space coordinates.
image047 Thus we have obtained the Lorentz transformation for events on the *x*-axis. It satisfies the condition *x′*2 – *c*2*t′*2 = *x*2 – *c*2*t*2 . . . . . . (8a). The extension of this result, to include events which take place outside the *x*-axis, is obtained by retaining equations (8) and supplementing them by the relations image048 In this way we satisfy the postulate of the constancy of the velocity of …
Einstein surveys how general relativity was tested: Mercury’s perihelion advance near 43 arcseconds per century, light deflection during the 1919 solar eclipse expeditions, and gravitational redshift of spectral lines.
(*a*) Motion of the Perihelion of Mercury According to Newtonian mechanics and Newton’s law of gravitation, a planet which is revolving round the sun would describe an ellipse round the latter, or, more correctly, round the common centre of gravity of the sun and the planet. In such a system, the sun, or the common centre of gravity, lies in one of the foci of the orbital ellipse in such a manner that, in the course…
Einstein argues that clocks in gravitational or rotating systems run at different rates depending on potential, treating atoms emitting light as clocks and predicting spectral lines shift toward the red near massive bodies.
image053 It may be added that, according to the theory, half of this deflection is produced by the Newtonian field of attraction of the sun, and the other half by the geometrical modification (“curvature”) of space caused by the sun. This result admits of an experimental test by means of the photographic registration of stars during a total eclipse of the sun. The only reason why we must wait for a total eclipse is…
In the Appendix on the structure of space, Einstein describes earlier static cosmology with an assumed constant matter density and radius, then notes Friedman’s expansion solution without a cosmological term, and links Hubble’s redshift observations to an expanding universe while highlighting a timing inconsistency.
of spectral lines be definitely traced to the gravitational potential, then the study of this displacement will furnish us with important information as to the mass of the heavenly bodies.[27] [27] The displacement of spectral lines towards the red end of the spectrum was definitely established by Adams in 1924, by observations on the dense companion of Sirius, for which the effect is about thirty times greater t…
Tocqueville explains why people cling to equality: it is harder to change, its downsides are delayed, its pleasures are immediate, and it often surges when rank barriers collapse.
holds out to them: equality is the distinguishing characteristic of the age they live in; that, of itself, is enough to explain that they prefer it to all the rest. But independently of this reason there are several others, which will at all times habitually lead men to prefer equality to freedom. If a people could ever succeed in destroying, or even in diminishing, the equality which prevails in its own body, this …
Zarathustra describes a “sublime one” who knows ugly truths but lacks laughter and beauty, then insists beauty is hardest even for the powerful, urging condescension as gracious transformation.
And this secret spake Life herself unto me. “Behold,” said she, “I am that WHICH MUST EVER SURPASS ITSELF. To be sure, ye call it will to procreation, or impulse towards a goal, towards the higher, remoter, more manifold: but all that is one and the same secret. Rather would I succumb than disown this one thing; and verily, where there is succumbing and leaf-falling, lo, there doth Life sacrifice itself—for power! …
He expands his lesson: what people call the worst wickedness is small and temporary, so larger “dragons” and a warmer south beyond current moral fear must come.
Verily, there is still a future even for evil! And the warmest south is still undiscovered by man. How many things are now called the worst wickedness, which are only twelve feet broad and three months long! Some day, however, will greater dragons come into the world. For that the Superman may not lack his dragon, the superdragon that is worthy of him, there must still much warm sun glow on moist virgin forests! O…
Vitruvius lays out what an architect must know: both practice and theory, and instruction in drawing, geometry, optics, arithmetic, history, philosophy, music, medicine, law, and astronomy, using them to judge and design works.
THE EDUCATION OF THE ARCHITECT 1. The architect should be equipped with knowledge of many branches of study and varied kinds of learning, for it is by his judgement that all work done by the other arts is put to test. This knowledge is the child of practice and theory. Practice is the continuous and regular exercise of employment where manual work is done with any necessary material according to the design of a draw…
Vitruvius describes how cinnabar yields quicksilver, detailing ore digging near Ephesus, drying in an oven, collecting mercury by its fumes and runoff, and using its behaviour to argue that gravity depends on nature not mere quantity.
NATURAL COLOURS As for colours, some are natural products found in fixed places, and dug up there, while others are artificial compounds of different substances treated and mixed in proper proportions so as to be equally serviceable. 1. We shall first set forth the natural colours that are dug up as such, like yellow ochre, which is termed [Greek: ôchra] in Greek. This is found in many places, including Italy, but …
Vitruvius explains how blue pigment is made from finely ground sand and natron with grated copper, then fired in jars and reduced to blue by heat; he also gives a recipe for burnt ochre using yellow ochre, heat, and vinegar.
BLUE. BURNT OCHRE 1. Methods of making blue were first discovered in Alexandria, and afterwards Vestorius set up the making of it at Puzzuoli. The method of obtaining it from the substances of which it has been found to consist, is strange enough. Sand and the flowers of natron are brayed together so finely that the product is like meal, and copper is grated by means of coarse files over the mixture, like sawdust, t…
He describes producing white lead and verdigris: in Rhodes lead shavings are soaked with vinegar under lids to turn white, copper plates likewise form verdigris, and white lead can be converted to sandarach by accidental-fire heating.
WHITE LEAD, VERDIGRIS, AND ARTIFICIAL SANDARACH 1. It is now in place to describe the preparation of white lead and of verdigris, which with us is called "aeruca." In Rhodes they put shavings in jars, pour vinegar over them, and lay pieces of lead on the shavings; then they cover the jars with lids to prevent evaporation. After a definite time they open them, and find that the pieces of lead have become white lead. …
Vitruvius defines machines and engines, categorizes types such as hoisting and pneumatic devices, and argues all machinery derives from natural motions of the sun, moon, and planets.
MACHINES AND IMPLEMENTS 1. A machine is a combination of timbers fastened together, chiefly efficacious in moving great weights. Such a machine is set in motion on scientific principles in circular rounds, which the Greeks call [Greek: kyklikê kinêois]. There is, however, a class intended for climbing, termed in Greek [Greek: akrobatikon], another worked by air, which with them is called [Greek: pneumatikon], and a …
Vitruvius lays out the physics of raising loads by combining straight-line motion with circular motion, using levers, windlasses, steelyards, ship steering, sails, oars, and balanced pole portage.
the wind, not when they are too close to the heel of the mast, which represents the centre, but when they have moved farther away from it to the top. 6. As a lever thrust under a weight is harder to manage, and does not put forth its strength, if the pressure is exerted at the centre, but easily raises the weight when the extreme end of it is pushed down, so sails that are only halfway up have less effect, but when …
Vitruvius gives construction principles for the water screw, using geometric layout to create spiral channels like a snail shell and describes its mounting and inclination for lifting water.
THE WATER SCREW 1. There is also the method of the screw, which raises a great quantity of water, but does not carry it as high as does the wheel. The method of constructing it is as follows. A beam is selected, the thickness of which in digits is equivalent to its length in feet. This is made perfectly round. The ends are to be divided off on their circumference with the compass into eight parts, by quadrants and o…
Continuing June 3–June 8, the expedition moves through a chain of creeks and islands, examines suspected lead sites, meets French traders from the Kansas River, navigates difficult sandbars, and describes salt-lick and mineral regions.
of junction is in latitude 38 degrees 31' 16", and at a short distance from it is a high commanding position, whence we enjoyed a delightful prospect of the country. The Osage river gives or owes its name to a nation inhabiting its banks at a considerable distance from this place. Their present name however, seems to have originated from the French traders, for both among themselves and their neighbours they are cal…
Locke defines solidity as resistance from touch that excludes other bodies from a space, distinguishes it from impenetrability, and claims it is essential to body at every scale.
IDEA OF SOLIDITY. 1. We receive this Idea from Touch. The idea of SOLIDITY we receive by our touch: and it arises from the resistance which we find in body to the entrance of any other body into the place it possesses, till it has left it. There is no idea which we receive more constantly from sensation than solidity. Whether we move or rest, in what posture soever we are, we always feel something under us that sup…
He argues solidity is distinct from pure space and hardness: bodies cannot surmount resistance while it remains, yet one can conceive space without solidity and illustrate with ideas from vacuum debates and a pump.
3. Distinct from Space. This resistance, whereby it keeps other bodies out of the space which it possesses, is so great, that no force, how great soever, can surmount it. All the bodies in the world, pressing a drop of water on all sides, will never be able to overcome the resistance which it will make, soft as it is, to their approaching one another, till it be removed out of their way: whereby our idea of solidity…
Locke differentiates solidity from hardness and contends that even soft bodies resist as much if they remain between others; he uses examples like air in a football and a water-filled gold globe experiment said to be made at Florence.
change figure by the pressure of any part of our bodies; and that, on the contrary, soft, which changes the situation of its parts upon an easy and unpainful touch. But this difficulty of changing the situation of the sensible parts amongst themselves, or of the figure of the whole, gives no more solidity to the hardest body in the world than to the softest; nor is an adamant one jot more solid than water. For, thou…
Locke argues that solidity is the body’s cohesion of separable parts, enabling impulse, resistance, and protrusion, and he criticizes those who claim clear ideas of space without bodies.
5. On Solidity depend Impulse, Resistance and Protrusion. By this idea of solidity is the extension of body distinguished from the extension of space:—the extension of body being nothing but the cohesion or continuity of solid, separable, movable parts; and the extension of space, the continuity of unsolid, inseparable, and immovable parts. Upon the solidity of bodies also depend their mutual impulse, resistance, an…
Locke says we should distinguish ideas as perceptions in minds from the material modifications that cause them, then names primary qualities—solidity, extension, motion/rest, number, and figure—as inseparable from matter.
6. Whether any ideas are due to causes really private. And thus one may truly be said to see darkness. For, supposing a hole perfectly dark, from whence no light is reflected, it is certain one may see the figure of it, or it may be painted; or whether the ink I write with makes any other idea, is a question. The privative causes I have here assigned of positive ideas are according to the common opinion; but, in tru…
Locke argues that bodies operate on us only by impulse and touch, transmitting motion via nerves and animal spirits to the brain, and he explains how primary and secondary qualities produce sensations through particles too small to detect.
12. By motions, external, and in our organism. If then external objects be not united to our minds when they produce ideas therein; and yet we perceive these ORIGINAL qualities in such of them as singly fall under our senses, it is evident that some motion must be thence continued by our nerves, or animal spirits, by some parts of our bodies, to the brains or the seat of sensation, there to produce in our minds the …