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ABSORPTION OF LIGHT.
The mode of absorption of light by a coloured substance is often tom. xli. p. 319) that the power of double absorption may be conferred eminently characteristic of the substance, but can be judged of only on naturally colourless crystals by a small amount of foreign impurity, very imperfectly by the tint of the transmitted light. It is easily A very remarkable example is afforded by nitrate of strontia coloured determined by analysing the transmitted light by means of a prism. red by crystallising out of an infusion of logwood.
When a body is not homogeneous in structure, but (like chalk or ABSTINENCE, from abstineo, io abstain. The term abstinence paper) is filled with surfaces capable of reilecting light, à considerable signifies a total, or an excessive privation of food. The constituent portion of the whole refiected light ordinarily proceeds from a greater matter of the body is in a state of continual change—the old particles or less depth beneath the outer surface. If the material of which the are constantly taken up and carried out of the system, while new body is composed be one capable of absorbing light, the light reflected particles are as regularly deposited in their room to repair the loss. from the interior suffers absorption both in penetrating into the body The source of these new particles is the aliment or food; but a second and in getting out again. Accordingly, those colours which the mate office is performed by the aliment scarcely less important than that of rial is least disposed to absorb are found predominating in the reflected furnishing new matter for the renovation of the system. All the light. It is thus that absorption operates in the case of pigments, the organs of the body are excited to the performance of their functions petals of flowers, dyed clothes, &c., which exhibit more or less lively by certain external agents, which are called stimulants; such as air, colours by reflected light, though in these cases the light reflected water, heat, and so on; but of these stimulants the aliment is among strictly at the outer surface is colourless. The tint of the reflected the most indispensable and the most powerful. Upon the quantity light has a general agreement with that of the light transmitted through and quality of the aliment depend the quantity and quality of the a sufficiently thin stratum of the coloured material.
| blood, and upon the quantity and quality of the blood depends in a Metals may for most purposes be regarded as absolutely opaque; yet great measure the energy of all the functions of all the organs. Any even they can sometimes be rendered so thin as to transmit light. , material change in the diet must necessarily produce a powerful imThus, gold-leaf transmits a green or bluish-green light; and the pression on the system. Life can be maintained but for a short coloration of the light shows that the transmission does not take period under the total privation of food, while the excessive privation place merely through the minute holes with which gold-leaf is filled, of it produces effects upon the system which have not been often but actually through the metal. There are good reasons for believing observed with accuracy, but which are remarkably uniform, and highly that the strong retlecting power of metals is intimately connected with curious and instructive. Opportunities occasionally occur of noting their intense absorbing power. Thus gold, which absorbs the more these effects with correctness and completeness, when, for example, refrangible colours with inost energy, reflects them also in greatest the passage to the stomach is closed up by disease; or when, owing to abundance, so that it is yellow by reflected, while it is bluish-green by an unsound state of mind, the individual rifuses to take nourishment. transmitted light. Some intensely coloured substances (murexide and During the first two or three days after the total abstinence from platinocyanide of magnesium are good examples) absorb the colours of food, in a person previously in sound health, the suffering from hunger a part of the spectrum almost as intensely as metals, while for other is generally severe. The thirst is also at times distressing, but thirst parts they are comparatively transparent, and reflect the colours for i is not constantly attendant. The pulse during this period remains which they have an intense absorbing power with an energy comparable natural and so does the temperature of the body. All the evacuations with metals : while other colours are reflected only as they would be are scanty, and take place at distant intervals. After the first two or by vitreous substances. Hence the regularly reflected light is brilliantly three days the wasting of the body becomes visible, the fresh colour coloured; but the predominant colour is that of the light most intensely characteristic of health disappears, and the features and the limbs, absorbed. This is just the reverse of what takes place in the case of instead of being plump and round, are sunk and collapsed. The loss the light reflected from the petals of flowers, &c., where the coloration of weight, which increases rapidly, is appreciable, and the progress of is due, not to reflection, but to absorption, and the colour is that due the emaciation is striking. The physical debility increases in exact to the light for which the absorbing power of the colouring substance proportion with the emaciation: and the mind becomes weak, conis least. (See a paper by M. Haidinger in the Proceedings of the fused, wandering, irritable, and at length almost deprived of reason. Academy at Vienna. Sitzungsberichte,' Bd. 8, S. 97. See also · Phil. All this time there is little or no pain from hunger or thirst, or these Mag.,' S. 4, vol. vi., pp. 284 and 393.)
| uneasy sensations return only at intervals, and are seldom acute and When a doubly refracting crystal is coloured, it often happens that never lasting. The pulse at this stage may be a little quickened; it is ho two pencils which, in any given direction within the crystal, are certainly easily excited; and in like manner the heat, which seldom capable of being transmitted independently of each other, are very sinks below the natural standard, is readily parted with, -so that a differently absorbed. Thus a plate of tourmaline cut parallel to the sligli change of the temperature of a room is felt acutely, and produces axis stops more or less completely light polarized parallel to the axis, very uneasy sensations, a fact which demonstrates to the physician the constituting the ordinary ray, and lets through light polarised perpen- feebleness with which the functions are carried on, no less clearly than dicularly to the axis, constituting the extraordinary ray. In some the physical debility itself. The most remarkable and curious pheno. specimens, with plates of a suitable thickness, the stoppage and mena which next supervene, are those connected with the intellectual transmission respectively are tolerably perfect, which makes such a faculties. The loss of power to perceive accurately, and to connect plate very valuable in experiments on polarisation. That the effect is the trains of thought, is followed by decided delirium, which is at first really one of absorption may be shown by using, instead of a plate of a low muttering character, similar to that which takes place in the bounded by parallel surfaces, a thin wedge tapering to a mere line, and last stage of typhus fever; but this sometimes passes rapidly into viewing it separately by light polarised parallel and perpendiculariy to furious and even maniacal delirium, requiring coercion, just as the axis
. It is found that quite close to the edge the crystal is violent paroxysm of madness itself. Generally the delirium is precolourless and transparent for both pencils; but that as the distance ceded by a state of painful watchfulness and restlessness, it being from the edge increases, the ordinary pencil becomes rapidly more and impossible to procure sleep or quiet; and, finally, the skin beconies more absorbed, while the absorption of the extraordinary comes on but intensely hot, the pulse extremely rapid, the emaciation frightful, the slowly. As usual in absorption, the different colours are unequally debility so great that scarcely the slightest movement can be performed, absorbed, and not only so, but the colours which are most absorbed and at length the individual sinks exhausted, commonly into a state are different for the ordinary and extraordinary rays, so that the crystal of stupor amounting to that complete and profound insensibility which is commonly differently coloured with regard to the two pencils, which is technically called coma. may be observed at the same moment, but separately, by viewing the This history of the progressive changes which take place in the crystal through a double-image prism. The mode of absorption system on the total abstraction of food, is illustrated in the most changes, not only in a given direction within the crystal in passing perfect manner, by two cases which fell under the notice of physicians from the ordinary to the extraordinary ray, but also in passing from capable of accurately observing and duly appreciating each successive one direction to another. Dr. Wollaston appears to have first event. Many wonderful stories are on record, of the truth of which observed (“ Phil. Trans.,' 1804, p. 428) that the light transmitted along there is no sufficient evidence; but the cases to which we refer were the axis of a crystal of tourmaline had a colour different from that observed and recorded by men whose veracity is beyond question, and of the light transmitted perpendicularly to the axis. Several uniaxal who were endowed with more than ordinary discrimination and judgcrystals (such as smoky quartz, &e.) agree with tourmaline in the ment. The record on this account is invaluable, while in itself it is general character of the absorption which takes place in them. The highly curious and instructive. colour, and generally the mode of absorption, of the ordinary ray is For the first case we are indebted to Dr. Currie, of Liverpool. In alike in all directions; that of the extraordinary varies from that of the August, 1795, a gentleman of Yorkshire, aged sixty-six, applied to this ordinary, which it has in the direction of the axis, to that most physician for his assistance, on account of an obstruction in his different from the ordinary, which it has in any direction perpendicular swallowing food, with which he had been afflicted for ten or twelve to the axis. Many biaxal crystals have a similar property, but the months. At first the complaint was slight; it occurred only when he variation of the colour with the direction is more complicated, and in attempted to swallow dry and hard substances; it afterwards extended particular some very curious appearances are observed about the optic to solids of every kind; and, at the time he was first seen by his phy.
(See a paper by Sir David Brewster, ' Phil. Trans.,' 1819, p. 11.) sician, although he was still able to pass down liquids, the quantity M. Haidinger has shown that in biaxal crystals (or at least in those he could swallow was not sufficient for his nutrition, and he was conwhich are symmetrical with respect to three rectangular planes) there siderably reduced. On the introduction of a bougie into the gullet, are three fundamental modes of absorption, symmetrically related to it passed about two inches easily, but then met with an obstruction the principal axes, seen each in any direction perpendicular to the axis which, by a moderate pressure, was overcome. It then passed easily in question by light polarised perpendicular to that axis.
seven or eight inches more, but at the lower part of the tube, towards M. de Senarmont has recently shown (‘Annales de Chimie,' $. 3, ! its termination in the cardia, it met with a firm resistance, which no
patience or skill could surmount. This obstruction proceeded from a 'jokes had passed, at the recollection of which he laughed heartily, a schirrous tumour, which, gradually increasing at first, diminished the thing uncommon with him; but it was observable that he was unable, passage, and at length closed it wholly.
| longer than a moment or two, to distinguish this scene which had On the evening of the 17th of October, a sudden increase of the passed in sleep from a real occurrence; and this state of mind lapsed obstruction came on, and from this time he was able to swallow only a into delirium from which he never recovered. At this period he was table-spoonful of liquid at a time, and at long intervals. It was with so weak as to be scarcely able to turn himself in bed, to which he had difficulty that he got down seven or eight spoonsful of strong soup in been entirely confined several days, previously to his death. the day, and this quantity gradually diminished. On the thirteenth The second case, which is no less interesting, occurred to Dr. Willan. day from this sudden increase of the obstruction, the passage appeared It was that of a young man of studious and melancholic turn of mind, to be wholly closed.
who being affected with indigestion, undertook voluntarily to live The patient himself, to the last, was far from despairing of his without food. He drank nothing but water flavoured with a little recovery; and the affectionate friends around him, though they could orange juice. He was seen by Dr. Willan on the sixty-first day of his not but see the issue of the case, yet desired that his life might be fast: at that time he was emaciated to a most astonishing degree; the prolonged to the uttermost. The following plan was, therefore, muscles of his face were entirely shrunk; his cheek bones stood proadopted with this view. Every morning a clyster was administered, minent and distinct, affording a most ghastly appearance; the abdomen consisting of eight ounces of strong broth, made chiefly of the mem was concave from the collapsed state of the intestines; the limbs were branous parts of beef, these being considered the most nutritious, into reduced to the greatest possible degree of tenuity, and the processes which were rubbed two yolks of egg, and to which were added forty of their bones were easily distinguishable. His whole appearance drops of laudanum. This was repeated in the afternoon, and again in suggested the idea of a skeleton prepared by drying the muscles upon the evening, previously to which, in the evening, he was placed up to it in their natural situations. His mind had become imbecile. the neck in a tepid bath, of which one-fourth was milk, and the rest Unfortunately the treatment adopted was injudicious, the quantity water; the whole quantity amounting to twenty-four gallons. The of food allowed him being much too large; yet, for the first few days, temperature was fixed at 96°, to accommodate his sensations, and the he appeared to improve, regaining flesh and strength, and acquiring time of immersion was gradually prolonged from forty-five minutes to firmness and even cheerfulness of mind; but on the night of the fifth an hour.
day he was sleepless and restless; on the morning of the sixth, he After a few days it was found that the retention of the rectum began to lose his recollection, and before midnight he was quite frantic improved, so that the clysters were enlarged to ten ounces of broth, and unmanageable; at the same time his pulse was increased in freand three yolks of eggs each; to which were added eight ounces of quency, with considerable heat of the skin, and tremors. During the white wine, and the laudanum, which was added to the evening following day he continued raving, and talking very incoherently, as clyster, was gradually increased from sixty to two hundred and fifty he had done during the preceding night. He remained nearly in the drops. Thus the whole of his nutriment for twenty-four hours con same state, scarcely ever sleeping, and taking very little nourishment, sisted of thirty ounces of broth, twenty-four ounces of wine, nine his pulse becoming daily smaller and feebler, and beating at length yolks of eggs, and from 250 to 380 drops of laudanum, and ad- 120 strokes in a minute, and his emaciation still increasing, until the ministered by clyster; with what liquid might be supposed to be eleventh day from the period that he began to take food and medicine, taken up in the bath by the absorbents of the surface of the body. and the seventy-second from the commencement of his abstinence, on
When in tolerable health, at the commencement of his complaint, which day he died, quite exhausted. this gentleman, who was a tall man, and naturally corpulent, weighed : There is no authentic case on record in which the duration of the 240 lbs. Before the obstruction had become complete, imperfect abstinence was as long as this, and both these cases taken together, nutrition had reduced him to the weight of 179 lbs. In twenty days, afford an excellent history of the disorder of the functions, and the from the period of the sudden increase of the obstruction, he was exhaustion of the powers of life on the total and continued abstraction reduced to 154 lbs. ; on the twenty-fourth day he had lost 5 lbs. more; of food. The mind in the first case was naturally firm and strong; in and at the period when his delirium commenced, that is on the thirty- the second it was supported by an enthusiasm amounting to insanity. second day from the night that he ceased to swallow, he weighed When the mind is feeble, and especially when it is under the influence 138 lbs., having lost upwards of 100 lbs. of his original weight He of fear, anxiety, despondency, or any other depressing cause, the lived four days longer, that is, thirty-six days from the period when duration of life is greatly abridged. It is instructive to observe the the obstruction was supposed to be complete; but during these last absence of severe suffering from hunger and thirst; the absence of four days, no nutriment, in any form or of any kind, was administered;, all acrimony of the fluids; the absence of all violence and turbulence for the rectum no longer retained the clysters, and the administration of mind until delirium set in, the precursor of death. of the bath appeared, under these circumstances, to be wholly useless. From the powerful influence of abstinence on the system, it is
For a month after the total obstruction of the passage the tem- obviously capable of becoming a most energetic remedy in various perature and the pulse were natural; but on the thirty-second day the diseases. When the mass of the fluids and solids of the body is too pulse became small and frequent; on the following day the eyes lost abundant, abstinence is capable of reducing them to almost any extent their common direction, the axis of each being turned towards the that can be required; and if the abstinence be judiciously commencen nose; he complained that he sometimes saw double, but the sensibility and conducted, not only is it unattended with any diminution of the of the retina was increased rather than impaired; for, on the admission' strength or injury to the health, but it contributes to the improveof the light of the window, he screamed out, though he had before ment of both. Numerous instances are on record which place this been accustomed to this light. On the next day there was considerable fact beyond question. The case of Cornaro the Venetian nobleman, incoherence of mind; this incoherence passed rapidly into delirium, and that of the Essex miller, which afford evidence of this mora during the prevalence of which there was a perpetual and indistinct complete than it would be easy to invent, are universally known. The muttering, with great restlessness and agitation; the skin and the body, whatever be its bulk or weight, provided the health be in other extremities were sometimes of a burning heat, and sometimes clammy respects sound, may be reduced to almost any degree of thinness, and and cold; the pulse became feeble and irregular; the respiration, kept at that point by an appropriate regulation of diet and exercise. which hitherto had been singularly undisturbed, became laborious; The physician, at his pleasure, can make no one fat, but he can make and in ninety-six hours after the clysters and all other means of any one as thin as he chooses, frequently improving at the same time nutrition had been abandoned, he ceased to breathe.
the health and vigour both of body and mind. Seldom is he called During the whole of this melancholy progress to inevitable death, upon to put this art into practice, and seldomer than he ought does he this unfortunate gentleman complained very little of hunger : occa- insist upon carrying it into practice; but it is something to know that sionally he expressed a wish that he could swallow, but not often nor the resources of his art place this in his power. anxiously; and, when questioned on the subject of his appetite, he In ali acute diseases, such as the various forms of fever and inflamalways declared that he had no hunger which occasioned any uneasiness. mation, abstinence is a most powerful remedy, not only because the The clysters evidently relieved the sense of hunger, and the opium abstraction of nutriment diminishes the mass of the fluids and solids they contained seemed to have a powerful share in producing this (since the process of absorption goes on though the supply of new relief. It occasioned quiet and rest after each clyster, and allayed matter is stopped), but also because it withdraws one of the main every kind of desire or appetite. Neither was he much disturbed with stimulants of the system, and consequently subdues the increased thirst. This sensation was, indeed, troublesome during the first days actions which accompany, and which for the most part constitute, of his abstinence; but it abated, and, as he declared, was always acute diseases. removed by the tepid bath, in which he had the most grateful sen In some chronic maladies, especially in that large class which depend sations. His spirits were uncommonly even, and his intelloct perfectly on what is termed plethora, that is, too great a quantity of solids and sound. He occupied himself a good deal in his private concerns; and, fluids, particularly in the plethoric state of the blood vessels of the as usual, interested himself in public affairs. In order to husband his brain, predisposing to and producing apoplexy, in some morbid strength he was confined a good deal to bed; but, till the last few days affections of the stomach itself, in some derangements of the liver, and of his life, he dressed and undressed himself daily, and walked, not in several diseases of the heart, abstinence is an invaluable remedy. only about his room, but through the house. His nights were quiet; In other chronic diseases it is injurious, as in diseases of debility, in his sleep sound, and apparently refreshing. Just before his delirium diseases which depend on irritation in contradistinction to those which set in he had very lively dreams, which were all of a pleasant nature; depend on inflammation, and in various nervous maladies. and, in the last conversation he had with his physician, he told him hé Abstinence is not equally borne by all persons, nor at all times by had had a very gay evening with two Yorkshire baronets whom he the same person. By the corpulent and plethoric it may be endured named; that they had pushed the bottle about freely; that many longer, and carried farther, than by the thin and the spare; in the
ABSURDUM, REDUCTIO AD. middle or mature aga, it is less injurious than in infancy, youth, or From these remarks it is evident that abstraction, being a mere extreme old age. A degree and duration of it, which are highly bene- arbitrary act of the mind, by which a certain attribute is considere ficial in a fever or an inflammation, would be fatal in the state of health. apart from any other attributes with which it may happen to be 235
It is curious, and it is highly important to bear in mind, that ciated, does not represent to us images or notions to which there is abstinence and excess produce symptoms so nearly alike, that it often anything corresponding in the nature of things; there is nowhere a requires the utmost care and sagacity on the part of the physician to abstract man or tree which has no colour, dimensions, or othe distinguish the one case from the other; and as the one requires incidents not entering into the abstract notion signified by thos opposite remedies from the other, a mistake may be fatal, and must be general terms. Whenever we recognise in any object those peculiarities injurious. A man, addicted to drunkenness, was cast into prison for which we consider as characteristic of a certain class, we refer it to theft, and reduced, at once, to a diet of bread and water. After the that class, without taking any heed of the other attributes with whaž first week, a disorder of the intellectual faculties took place; his they may happen to be combined. Thus, if in some unexplored parts countenance became pale and expressive of languor, his flesh wasted, the world there should be discovered a race of animals resembling som and his strength declined; his nights were sleepless; shortly after known variety of the human race in every particular except the colme wards there was delirium, which was mild at first, but subsequently of the skin or the hair, they would be doubtless called men, althougt furious. These symptoms might have been easily mistaken for those there is no such thing as an abstract man whose skin or hair is devoid which denote inflammation of the brain; but the true nature of the of colour. affection was discriminated, and brandy was administered. Immediately The circumstance of there not being any sensible object, or any the affection of the brain disappeared, and the flesh and strength conception of our mind, which we can image to ourselves without it returned.
attributes, has given rise to considerable perplexity on the subject Some time ago an alarming epidemic broke out in the Milbank abstraction. For instance, when we think of a horse, we represent tə Penitentiary, London. The prisoners confined in this prison were ourselves an animal of certain colour, shape, and size ; though we suddenly put upon a diet, from which animal food was almost entirely should equally give the name of horse to an animal of different color, excluded. An ox's head, the meat of which weighs eight pounds, was shape, and size. So, when we think of a plane triangle, although a made into soup for one hundred people, which allows one ounce and a triangle is any plane figure bounded by three straight lines, yet we quarter of meat to each person. The prisoners were at the same time cannot help representing to ourselves a triangle which is either rightsubjected to a low degree of temperature, to considerable exertion, and angled, or acute-angled, or obtuse-angled, or equilateral or scalene. were confined within the walls of a prison, situated in the midst of a The truth is, that the process by which the mind abstracts is, that it marsh, which is below the level of the adjoining river. The con-, conceives or represents to itself the object of thought as an individual sequences were, first, loss of colour, of flesh, and of strength; next, of its class, together with certain particular attributes which must this simple debility of constitution was succeeded by various forms of belong to all individuals; and it considers apart from the rest only disease-scurvy, dysentery, diarrhea, low fever; and, lastly, affections that attribute which is required for the matter in hand. Thus, if it is of the brain and nervous system-namely, headache, vertigo, delirium, a question whether a newly-discovered skeleton is that of an anima? convulsions, apoplexy, and even mania. When bleeding was tried, the belonging to the class of elephants or of deer, the comparative patients fainted after losing five, four, or even fewer ounces of blood. anatomist calls to his mind an elephant or deer, such as actually exists, Abstinence will sometimes produce a train of symptoms exactly similar but considers only the structure of his bones; and, if there is a close to those of the disease which it is employed to remove. Persistence in agreement in this respect, he pronounces the skeleton to have belonged the abstinence will aggravate the malady, which will baffle every mode to one of those classes. So, likewise, when a mathematician, by means of treatment as long as the abstinence is persevered in; but which of a figure described on paper, proves that the square of the hypotenuse will disappear with surprising rapidity on the administration of a equals the sum of the squares of the other sides of a right-angled generous diet. This is especially the case with those affections of triangle, although the image in his mind is that of a triangle of a simple irritation which assume the appearance of inflammation, and definite size, yet he considers only the relation of the sides and angles, which are attended with headache, noise in the ears, giddiness, restless- without paying any attention to the length of the lines. ness, sleeplessness, and delirium. A professional man was seized with This process, by which the mind generalises a particular notion, by fever; rigid abstinence was enforced, not only during the continuance considering only a part of it, might be illustrated by many examples of of the fever, but also during the stage of convalescence. Delirium, changes in the meaning of words. Thus, there stood formerly on the which had been present in the height of the fever, recurred in the bank of thie Thames, in London, a palace called Bridewell; this, in the convalescence. A physician of eminence in maniacal cases was con- | reign of Elizabeth, was converted into a penitentiary, or prison for hard sulted, who recommended him to be removed to a private asylum. labour; whence the term bridewell has been extended, and is now Before this advice was carried into effect, another physician saw him : sometimes used as a general name for such penitentiaries. So the a different treatment and regimen, with a gradual increase of nourish- name palace has been extended to all sumptuous houses, having ment, were adopted; the patient was well in a few days, and within originally been confined to that on the Palatine hill, at Rome. It has a fortnight returned to his professional avocations.
been remarked that, although brute animals have, like men, the faculty It is the common belief that abstinence is conducive to longevity, of reasoning or drawing conclusions from premises, yet they have not, and many stories are on record which are conceived to establish the like men, the faculty of abstraction. Nevertheless, it is plain that truth of this opinion. It is stated, for example, that the primitive some animals go through a process of which the effects exactly corChristians of the east, who retired from persecution into the deserts of respond with that of abstraction in men ; for example, they can count, Arabia and Egypt, lived healthfully and cheerfully on twelve ounces of and are aware of the recurrence of certain numbers; and a dog who bread per day, with mere water; that, with this diet, St. Anthony has once been beaten with a stick, or pelted with a stone, will run away lived 105 years; James the Hermit, 104; Arsenius, tutor of the from all sticks or stones, of whatsoever size, shape, or colour. That they Emperor Arcadius, 120; St. Epiphanius, 115; Simeon the Stylite, 112; cannot found, on abstraction, the admirable gift of language, the most and Romauld, 120: to which are added many others. But we should important distinction between men and beasts, is owing apparently not remark that the evidence for these instances of longevity is not very to the absence of the power forming general notions, nor yet to the satisfactory. (Food, in Nat. Hist. Div.]
inability of making articulate sounds, as we may perceive in the ABSTRACT. [VENDORS AND PURCHASERS.]
instance of the parrot. [NOMINALISTS.] ABSTRACTION is an act of the mind, by which it considers a ABSURDUM, REDUCTIO AD), is that species of argument which certain attribute of an object, or several objects, by itself, and without proves, not the thing asserted, but the absurdity of everything which regarding any other attributes which the object or objects may happen contradicts it. It is much used in geometry, in order to demonstrate to possess. Thus, if we see ink, pitch, ebony, and a negro, we see that the converse of a proposition already proved. One of two things must these objects have in common the attribute of blackness; and this be true ; either the proposition asserted, or something which contraquality we can in thought draw off' or abstract from the various other dicts it. If the opposing party deny the proposition, he must affirrn attributes which they respectively possess; and consider it separately that which is contradictory. Let his counter-proposition be taken for and independently of anything else. In like manner we can consider granted; then, if by the legitimate use of it some absurdity can be any attribute of a single object, such as of the sun or moon, without deduced, it is evident that his contradiction is wrong, and the original attending to its other attributes; thus we may contemplate the magni- proposition right. As an instance of this method of proceeding, let us tude of the sun without attending to its heat, light, &c.; so we may suppose it has been proved, and is not denied, that whenever a iş B contemplate the light of the moon, without attending to its magnitude, then c is D. We may then affirm that when ó is not D. A is not B. the inequalities of its surface, &c. All names of classes, inasmuch as For if a were b, c would be d; but c is not d, therefore A is not B. the individual members can never be identical, are formed by a process. The full form of the Reductio ad Absurdum, in this case, is as follows: of abstraction. Thus, when we think of a ship or a house, we pay no -You grant that if a were B, C would be D; but you refuse to admit attention to the materials, colour, shape, size, construction, convenience, the consequence that, when o is not D, A is not B; that is, you say or beauty of the ship or house, but we give the one name to any that c may not be D, and yet A may be B. Let this, then, be as you dwelling of man built by regular artificers, and the other to any vessel say, that is, let o not be D, and yet let a be B. But in supposing that with a deck and masts made to sail on the sea. Any object which A is B, the admitted proposition obliges you to say that c is D. But possesses these attributes we call a ship or a house ; though there you have supposed that o is not D: you therefore say at the same time cannot be any ship or house which possesses only those attributes, and that c is d, and that c is not D, which is absurd. Consequently, if it is not also of a certain colour, size, shape, &c.; but these incidental be true that whenever a is B then o is D, it follows that when c is not qualities we leave out of our consideration in referring any object to D, A is not B. the class of houses or ships.
The Reductio ad Absurdum has been objected to as not equally
conclusive with direct demonstration. For this there is no foundation; names of Aizanas and his brother Saizanas, both of which occur in the though it must be admitted that direct demonstrations are more inscription, and also in a letter of the Emperor Constantine, addressed pleasing and more elegant. But it is obvious that, if everything which to them A.D. 356. When the Greek merchant Cosmas visited contradicts a proposition be false, the proposition itself must be true. Abyssinia, A.D. 525, it was completely a Christian country, and well The student of logic must distinguish between that which is only provided both with ministers and churches. Of the Abyssinian contradictory, and that which is contrary to a proposition. Thus, to churches, which probably belong to the earlier periods of their converthe proposition that “all squares are equal,” it is contradictory that sion, or at least are eight or nine hundred years old, there are still
some squares are not equal," and contrary, that "no squares are some remains. The most remarkable is Abuhasubha, hewn out of the equal.” The contrary is the most complete contradictory, and affirms solid rock, which at this place is soft and easily worked. The Portuthat the proposition is true in no one instance. It is not correct to guese, Alvariz, describes ten such churches as these, of which he has say that, if a proposition be false, its contrary is true; for example, it given a plan, and one of them is probably the same as that which Mr. is false that all squares are equal, and equally false that no squares are Pearce visited at Jummada Mariam. (Salt, p. 302.) The great church equal. But of a proposition and its contradictory one must be true; at Axum is comparatively modern, though parts of it, such as the thus either all squares are equal or some squares are not equal. Hence, steps, clearly belong to å prior edifice. Mr. Salt describes the wellwhatever disproves a proposition proves something contradictory, and built remains of a church or monastery near Yahee, which he assigns to whatever disproves everything contradictory proves the proposition. , the 6th century of the Christian era. The Reductio ad Absurdum is, therefore, as conclusive as direct demon The monastic, and also the solitary life, spread into Abyssinia from stration.
the deserts of the Thebais, and when the Portuguese Jesuits entered The Reductio ad Absurdum, in Euclid, is wholly unnecessary to all the country they found it full of such devotees; many of them seemed, who can see that contra-positive propositions are identically the same. however, to be monks only as far as celibacy was concerned, for they The following forms are contra-positive :
cultivated the ground and lived in villages. Every A is B
With the Christian religion, the Abyssinians received the Holy Every not-B is not-A.
Scriptures, which they now possess in the ancient Ethiopic version, Thus (Euclid I. 4) two sides equal to two sides understood, proves that made, according to Ludolf, from the Greek Septuagint, though nothing equal angles give equal areas : that is, unequal areas give unequal is known of the date of this version. As to the New Testament (says angles. He then has to prove I. 6, which he does by Reductio ad Ludolf), no entire copy has been yet brought to Europe. Mr. Bruce Absurdum. His form is, equal base angles give equal opposite sides : brought with him from Abyssinia a complete copy of the Scriptures in its equivalent contra-positive is, unequal sides give unequal opposite the Ethiopic language, and also a set of the Abyssinian Chronicles. angles. From the unequal sides it may immediately be shown, as in The Abyssinians divide the Scriptures, which they have entire, differEuclid, that two triangles having two pairs of sides equal, each to each, ently from what we do, making four principal parts of the Old Testahave unequal areas, and therefore unequal angles. Thus it is shown ment, and mixing what we call the Canonical with the Apocryphal that the angles opposite unequal sides are unequal : which is but books. The New Testament is also divided into four parts, to which saying that the sides opposite equal angles are equal. Had logic been they add the Book of Revelation as a supplement. The old written cultivated concurrently with geometry, the Reductio ad Absurdum language is of the Semitic stock, and is written from left to right, but would long ago have disappeared, in nearly all the cases in which it is the language is not now spoken ; there are two languages now in use, now used.
the Tigré and the Amharic. For other information respecting the ABUTMENT, in building, is that which receives the end of, and Abyssinian liturgies, and the religious opinions of the Abyssinians, we gives support to, anything having a tendency to thrust outwards in a refer to Ludolf, Book iii. chaps. 4,5. Ludolf denies the existence of horizontal direction. The piers against which an arch that is less than the Book of Enoch, because he had only seen a spurious copy. A a semi-circle rests are abutments; while the supports of an arch of any knave who got possession of an Ethiopic book, wrote the name of Enoch other figure, which springs at right angles to the horizon, are imposts. upon it, and sold it to Peiresc for a considerable sum of money, and The piers of the arches of Southwark and Vauxhall bridges are abut- this was the book that Ludolf saw. Bruce brought home three copies ments or abutment-piers; whereas those of London, Blackfriars, and of the book of Enoch; one of which he gave to the, Bodleian Library Waterloo bridges, and of the old Westminster bridge, are imposts or at Oxford. This book was originally written in Greek, but the original impost-piers. Nevertheless, the piers at the extremities of a bridge, of is lost--all but one large fragment. In the epistle of Jude reference whatever form its arch or arches may be, are always termed its abut- is made to the prophecies of Enoch; and Mr. Bruce says," the quotaments; that is, abutments of the bridge itself.
tion is word for word the same in the second chapter of the book." ABUTMENT, in machinery, is a term applied to a fixed point from This, however, will not prove the genuineness of the prophecies of which resistance or re-action is obtained. In an ordinary steam-engine, Enoch, as Mr. Bruce has very well argued. An English translation of for example, each end of the cylinder acts alternately as an abutment. the book of Enoch was published by Dr. Lawrence, Oxford, 8vo. 1822. The steam, being unable to expand itself in the direction of the fixed The High Priest (or sole bishop) of Abyssinia is called Abuna, which obstacle, that is, the end of the cylinder, expends the whole of its elastic signifies Our Father; and as Frumentius, the first bishop, received his force in the opposite direction, against the movable obstacle or piston. appointment from the Patriarch of Alexandria, this dignitary has, proIu like manner the breech of a gun forms an abutment for the expansive bably, always been a foreigner. The king is the head of the Church. force of the ignited powder; although in this case, the abutment not Polygamy, though not allowed by the ecclesiastical canon, is common being absolutely a fixed point, its recoil occasions some loss of power. enough in practice; and Mr. Salt mentions an instance of one gentleEven a rotatory steam-engine, with a continuous circular action, must man who had five wives at once. The king, of course, marries as many have an abutment to render the force of the steam effective. Springs, as he pleases: the clergy, also, who are not monks, may marry, but whether used to impel machinery, as in the case of a watch, or to only once. A second marriage renders them unworthy of their sacred measure or control force, as in the various contrivances noticed under office, according to the ancient canons. Circumcision, according to SPRING-BALANCE, must have their abutments or points of resistance; Bruce, is practised in Abyssinia, and baptism of infants and agapæ or as also must all mechanical combinations in which power is trans- love-feasts have been in use ever since the introduction of Christianity. mitted by means of screws, of which it is sufficient to cite as an example The creed of the Abyssinian Church is what is called the Monophyiste; the nut in the fixed head of an ordinary screw-press. In all these cases i. e., admitting the divinity of our Saviour, but acknowledging in him an analogy may be traced with the use of the term abutment in archi- only one nature. tecture. With a similar meaning the name is applied in carpentry to a It would appear, from what we know of the Abyssinian Church, joint in which two pieces of timber meet so that the fibres of one piece that its priests, at present, are not well informed, nor are the people in run in a direction oblique or perpendicular to the joint, and those of the general well acquainted with the principles of the Christian religion, other parallel with it.
though they may be Christians in name; yet some of their ceremonies ABŪTTALS, from the French abutter, to limit or bound, are the are conducted with great decency, and very much resemble those of buttings and boundings of lands to the east, west, north, and south, the Church of England. When Šalt was at Chelicut, Lent was strictly showing by what other lands, highways, hedges, rivers, &c., such lands observed for fifty-two days, and no flesh was eaten during this period, are in those several directions bounded.
though fish and various dishes were always plentiful on the table: the The bourglaries and abuttals of corporation and church lands, and of people always fasted till sunset. A feast followed this severe and parishes, are usually preserved by an annual procession.
protracted fast, in which they all seemed anxious to make up for lost ABYSSINIAN CHRISTIANS. The discovery of a body of Christians time, by over eating and drinking. The Sacrament is also administered in so remote a country excited, in no small degree, the attention of in Abyssinia, in a very decorous manner; and red wine made of a Europe in the 15th century, which was again revived by Salt's last grape which is common in some parts of the country, is used on the mission, in 1810. From the Tareek Negushti,' or 'Chronicle of the occasion. Formerly (says Mr. Salt) if a man married more than one Abyssinian Kings,' combined with the evidence of the ecclesiastical wife, he was excluded from participating in this rite, but wealth and writers, we learn that Christianity was introduced into Abyssinia in power have induced the Church to relax its severity in this respect. the time of Constantine, by Frumentius, or Fremonatos, as the Marriage itself in Tigré, appears a mere civil institution : the woman chronicles call him. Frumentius, after residing some years in the keeps her name, and the parties can separate whenever they agree to country, was raised by Athanasius the patriarch of Alexandria, to the do so. In this case the woman has her dowry back, which is not dignity of bishop: tie arrived in Abyssinia, perhaps about the year forfeited unless she is manifestly guilty of adultery. The higher classes A.D. 330, and probably in the reign of the King Aizanas, whose name are subject to no rule, but what may be considered as imposed by the still exists in the inscription of Axum. It is, however, not certain to relatives of the male and female.
The priests are forbidden to marry which king of the Abyssinian chronicles we ought to apply the after ordination. The Abyssinians bury their dead immediately after
washing and fumigating the body with incense : while the bearers are the Impartials), and the Academia Fiorentina, originally the Academia putting it in the ground, the priests recite a form of prayer. Other degli Umidi, founded in 1519 by Cosmo I. The united institui. strange ceremonies that follow are described by Salt.
tions bear the name of the Royal Florentine Academy. Another (Ludolf's History of Ethiopia ; Bruce, vol. ii. p. 422 ; Salt's Abyssinia ; very famous old Florentine academy is that entitled Del Cimento, Rüppell; Gobat, Journal of a Three Years' Residence in Abyssinia ; and that is, the Academy of Ecperiment. It was instituted for the Professor Lee's Brief History of the Church of Abyssinia, prefixed to cultivation of physical science, by the Cardinal Leopold de' Medici, that work.)
brother of the Grand Duke Ferdinand II., in 1657. Among its ACADEMY. A house and garden in one of the suburbs of Athens, first members were Borelli, Viviani, &c. A collection of experiments inclosed by a wall, and having the grounds laid out in walks shaded by on the pressure of the air, the compressibility of water, on heat, trees, was the original Academy. It is commonly stated to have been sound, projectiles, light, and other subjects belonging to natural so called from its original possessor Academus, or Ecademus, who is philosophy, was published in Italian by the Academy del Cimento in said to have established here a school of gymnastic exercises. Other 1667, of which Muschenbroeck afterwards give to the world a Latin etymologies of the term, however, have also been given. About the translation, with valuable notes. Many of the Italian academies are middle of the 5th century before the commencement of our era, the remarkable for the fantastic names by which they are designated; and groves of Academus fell into the possession of Cimon, the Athenian in 1725 there were nearly 600 of them. The Royal Academy of general ; and it was he who first adorned the place with statues and Sciences and Belles Lettres Naples was founded in 1779; it has fountains, and added other improvements, so as to convert it into a published its Transactions, which contain many valuable papers on retreat uniting to the charms of natural scenery many of the luxuries mathematical subjects, since 1788. The Herculanean Academy of Naples, of art. At his death he left the garden to the public; and it became was founded in 1755; the first volume of its Transactions appeared a favourite resort of the lovers of philosophy and solitary meditation. in 1775, under the title of ' Antichità di Ercolano,' and it has been Hither Socrates was wont occasionally to repair to converse with his followed by several others. The Academy of Etruscan Antiquities disciples. But it was his illustrious pupil, Plato, who first gave at Cortona, founded in 1726, and that at Florence, founded in celebrity to the Academy as the seat of philosophy, by establishing 1807, have both published valuable Transactions. There are also here the school over which he presided for nearly half a century. academies at Padua, Milan, Siena, Verona, and Genoa, by all of which Hence the Platonic philosophy is frequently called Academism, or the some volumes of Transactions have been printed. The Academy of philosophy of the Academy; and its followers, Academics, or Academists. Bologna was originally founded in 1690, by the afterwards distinguished Plato died about the year 348 before the Christian era. About the astronomer Eustachio Manfredi, then only sixteen. The associates year B. C. 296, one of his successors, Arcesilaus, introduced certain called their institution the Academia degli Inquieti, and took for their changes into the original doctrines of the school; and he is on this motto the words Mens agitat. In 1714 this academy was united to the account considered the founder of a second, or Middle, as distinguished University or Institute of Bologna, since which event it has been from the Old academy. There was also in this sense a third academy,' called the Academy of the Institute, or the Clementine Academy (from called the New, of which the founder was Carneades, who flourished Clement XI., the then Pope). Its Transactions have been published about a century after Arcesilaus. Some writers even reckon a fourth under the title of 'Commentarii,' since 1731. To this list we may add Platonic academy, founded soon after the time of Carneades, by Philo' the Royal Academy of Turin, in Piedmont, which was originally a (not the celebrated Platonic Jew), and Charmidas or Charmadas; and private association founded about the middle of the last century, by a fifth, designated the Antiochian, from its founder, Antiochus, who the young Lagrange, then, although not yet twenty years of age, holding had been a disciple of Philo. With regard to the academy of Plato, the office of Professor of Mathematics in the Royal Artillery School of we may further notice that it was situated in the suburb, lying N.W. that city. The first volume of its Transactions was published in of Athens, called Ceramicus, that is, literally, the Place of Tiles; and Latin, in 1759, and surprised the scientific world by some papers of it has been remarked, as a curious coincidence, that the principal public great originality, to which the name of Lagrange was appended. The garden of that city should thus have apparently had the same origin Turin Transactions, which continued for some years to be enriched by with the Tuileries of the modern capital of France, a name which also the contributions of this eminent mathematician, were published in indicates that the site was anciently that of a tile-work. Cicero had Latin, till 1784, since which time they have appeared in French. a country seat on the Neapolitan coast, to which, as one of his favourite The Académie Française was instituted in 1635 by Cardinal retreats for philosophical study and converse, he gave, in memory of Richelieu, for an object of the same nature with that proposed by the famous Athenian school, the name of Academia. It was here he the Academia della Crusca,--the purification, regulation, and general wrote his Academic Questions. Its remains are still pointed out near improvement of the national tongue. This society, in imitation of Pozzuoli, under the name of the Bagni de' Tritoli.
its Italian model, published in 1694 the first edition of a French After the restoration of letters in the 15th century, the term Dictionary, known by the name of the Dictionary of the Academy, to Academy was revived in Italy, but with a signification somewhat which it afterwards made many additions in successive reprints. This different from what it had borne in ancient times
. It was used to work however has scarcely perhaps attained the same authority with imply, not a school in which philosophy was taught by a master to his that of the Della Cruscan academicians; partly owing, no doubt, to pupils
, but an association of individuals formed for the cultivation of the comparative immaturity of the French language when it was learning and science, and usually constituted and endowed by the head of thus attempted to restrain its further growth. The original number the state in which it was established. What was now called an academy, of the members of the Académie Française was forty, from whom were in fact, more nearly resembled what was anciently denominated a elected a director and a chancellor every three months, as well as a Museum,--the name given, for example, to the famous association of secretary, who held his ofiice life. This constitution it continued the learned, founded by the first Ptolemy, at Alexandria, which so to retain till the year 1793, when it was abolished, with most of the long subsisted in that city. The Emperor Charlemagne is also recorded,' other establishments which had subsisted under the ancient govern. towards the close of the 8th century, to have established in his ment. Two years after it was restored as part of the Institute, palace at Paris a society of this description. Charlemagne was also the The next of the French academies, in point of antiquity, is the founder of the University of Paris, and several other schools and 'Académie Royale des Inscriptions et Belles Lettres.' It was established seminaries of instruction ; but although the Greek term Academia has in 1663, in the reign of Louis XIV., by Colbert, and consisted originally often, at least in more recent times, been applied to such institutions, of a few members selected from the Académie Française. In 1701 they are altogether distinct in their nature from what is properly this academy was placed, by an edict of the king, upon a new and called an academy.
more extended foundation; and from this date it published every On the other hand, many of those associations of the learned, which, year a volume of memoirs, many of great value, till it was suppressed in all material respects, resemble the academies that arose in Italy with at the Revolution. It consisted, at the period of its suppression, of the revival of letters, are, nevertheless, not known by that name. ten honorary members, ten pensionaries, and twenty associates, exclu. They are called not academies, but Societies, Associations, Museums, sive of several corresponding members. The 'Académie Royale des Lycæums, Athenæums, Institutes, &c. Of such associations, British Sciences' was originally established by Colbert in 1666, but was and foreign, which have issued, and many of which continue to issue entirely remodelled in 1699. By the new constitution its researches their printed Transactions, Journals, or various works, the Catalogue were confined to the department of the physical sciences. The of the British Museum contains a list of about 1250. Among the Académie des Sciences first began to publish its Transactions in 1666, more celebrated, and one of the earliest, was the Academydella and from 1699 a volume appeared regularly every year till the academy Crusca, that is, literally, of the bran, or choff', in allusion to the object was suppressed in 1793. These three academies, together with the of its institution, the purifying of the national tongue, and the sifting, Académie Royale de Peinture et de Sculpture, which had been rather as it were, of its flour from the bran. It was established at Florence a school of painting than an association of cultivators of the art, were in 1582, principally by the exertions of the poet Antonio Francesco restored by the Directory in 1795, and united into what was called the Grazzini, who is much celebrated for the purity of his style. The National Institute. The French Institute has, since its establishment, Dictionary of the Academia della Crusca, first published under the title ranked as the very first of the scientific associations of Europe, the of Vocabolario degli Academici della Crusca,' at Venice, in 1 vol. fol., most illustrious of whose philosophers have usually been comprehended in 1612; but augmented, in 1729-1738, to 6 vols. fol., is considered as in the list of its members. the standard authority for the Italian language; and the writers from The Royal Academy of Spain, founded at Madrid, in 1714, princi. whose works it has been collected. or whom it recognises as classies, pally by the exertions of the Duke of Escalona, was constituted on the such as Boccaccio, Machiavel, &c., are hence frequently denominated model of the Academia della Crusca and the Académie Française, and Autori
incorporated with has for its object the improvement and purification of the Spanish two still older
Satici (or Academy of language, of which it has published a Dictionary, under the title of