« EelmineJätka »
England, having a small independence, he retired into the country, entered into holy orders, and married a lady named Ensor, said to be a descendant of Shakspeare. He died in 1758, shortly after the publication of his longer poem ‘The Fleece, having gradually improved his fortune. “The Fleece' is a long unreadable poem, of a purely didactic kind. The middle of the last century was remarkably prolific in poems which took for their model Virgil's ‘ Georgics." Dyer’s ‘Fleece, Grainger's “Sugar-cane,” and Phillips's ‘Cyder,’ are all of this class. By selecting subjects essentially unpoetical, whatever might be the ingenuity of the writers, they could do no more than make a tolerable poem of a bad kind; for they did not confine themselves to a mere outline of the subject, which they might fill up with what colouring they pleased, but essayed to give, in a poetical form, the intricacies and minutiae of various branches of manufacture. The selection of Virgil's “Georgics' for a model was in itself a fallacy, as we question whether this work, with all its beauties, would be much read at the present time were it not for the opportunity which it affords of studying one of the most elegant writers of the Augustan age, and for the light it throws on the agriculture of the antients. The “Ruins of Rome,” with here and there a fine line, seldom rises above mediocrity, and is a very heavy performance. It is on the poem of his youth, “Grongar Hill,’ that Dyer's reputation depends. There is, perhaps, no depth of thought, no new idea in this work, but it is a most vivid and brilliant combination of pleasing images. The poet invokes the muse to “draw the landskip bright and strong.’ and the muse seems to grant his request. We may conceive the poem to be the work of a man walking up-hill, and struck with the succession of scenery which opens all around, he says the first thing that comes into his head; and as he is affected by none but beautiful prospects, what he says is sure to be pleasing. ‘Grongar Hill' will always be a general favourite. DYKE (in Geology), a fissure caused by the dislocation of strata, commonly also termed a fault. Dykes are of frequent occurrence, and often extend several miles, penetrating generally to an unknown depth. They must have been produced by some violent disturbances, and the amount of dislocation of necessity would vary in proportion to the intensity of the disturbing force. Accordingly there are many dykes of great width and extent, which materially affect the face of the country in which they occur, while there are others so slight that it requires much care and observation to ascertain their existence. The strata are in most cases uplifted on one side of the dyke much higher (varying many fathoms) than those on the other side, and produce an apparent irregularity of strata most perplexing to the geologist. Sometimes it happens that, without any irregularity of surface, two distinct strata appear to form a continuous line, as in the Black Down Hills in Devonshire. [CRETACEous GROUP.] In some cases, however, dislocation is found without any alteration of the level of the strata on either side, but the appearance of the strata immediately adjacent to the fault sometimes affords proof of the action of fire. [CoAL FIELDs.] Dykes are of two distinct characters, depending upon the manner in which they have been filled up, and the substance of which they are composed. Dykes of the first description are those into which igneous rocks are supposed to have been injected in a state of fusion, and now appear as a consolidated mass. [BAsALT.] In the second the fissures are filled with the debris, sometimes mixed with clay, of the dislocated strata through which they pass. In some cases the fissure has evidently remained unoccupied for a long period, and the filling up has proceeded gradually from the sides inwards. This is observed very evidently in the carboniferous limestones of England and Wales. Sometimes, in consequence of the great length of time intervening between the production of each coating of calcareous matter, the outside of each is covered with crystals, upon which the next layer has been formed: in the central portions of such fissures cavities are by no means uncommon. DYLE. [SchelDE.] DYNA'MICS (Čivapac, force), a word of comparatively modern use, now universally adopted as signifying the science of matter in motion, as distinguished from statics, which relates to matter at rest. Under so general a term, our plan requires us simply to refer the reader to the several articles connected with the subject.
Dynamics may be divided into two distinct parts: the mathematical consideration of motion, without reference to any connexion with its cause; and the experimental investigation of the connexion between pressure and the motion produced by it, together with the mathematical exhibition of the laws under which the second is a consequence of the first. The former branch is purely mathematical, and will be further treated under the head Motion, RELATIve; the latter will be found, as to its experimental part, under Motion, LAws of; and as to the mathematical part, under FoRCEs, IMPREssed and EFFECTIVE, and VIRTUAL VELocities, PRINCIPLE of. We need not suggest that such articles as Force, GRAviTATION, ATTRAction, PERGussion, FR1ction, &c. &c. contain the details of matters connected with the general term dynamics. The history of dynamics is particularly connected with the names of Galileo, Huyghens, Newton, D'Alembert, and Lagrange. See also on this point MECHAN1cs, the general term under which statics ...] dynamics are included. DYNAM'OMETER (measurer of power), a term which has been applied to an instrument which measures any thing to which the name of power has been given, whether that of an animal, or (to take a very different instance) of a telescope. We have also seen the incorrect term dynometer. DYNO’MENE, a genus of brachyurous crustaceans belonging to the division Notopoda, founded by Latreille. Character—Ocular pedicles longer than those of Dromia. Shell wide, nearly heart-shaped and truncated posteriorly, hairy or i. Two posterior feet only dorsal, and
much smaller than the others. Example, Dynomene hispida, the only species known to ocality, Isle of France.
DYRRA/CHIUM. [DURAzzo.] DY'SENTERY (Avrov.rspia, Dysenteria, from oc, with difficulty, and ivropov, intestine; difficultas intestinorum, bloody fluor), a disease in which there is difficulty and pain in passing the stools, which consist of mucus and blood, containing little or no facculent matter, and generally attended with sever. The desire to evacuate the bowels is frequent and urgent; but the effort is accompanied with severe pain, and is often altogether ineffectual, constituting the affection called tenesmus. What scanty stools are assed consist, as has been stated, of mucus mixed with lood, or of pure blood in considerable quantity; and if any faculent matter be present, it is commonly in the form of round and hard balls called scybalae. There is always griping pain in the abdomen. More or less fever is invariably present. The seat of the disease is chiefly in the large intestines: the disease itself consists essentially of inflammation of the mucous membrane. The forms of this disease, the causes which produce it, the circumstances under which it prevails, the pathological conditions on which its essential characters depend, and its degrees of intensity, are infinitely various; and these modifying influences cause it to assume at different seasons, in #. climates, and in different constitutions, the most diversified aspects. It is sometimes a primary, sometimes a consecutive, and sometimes a symptomatic disease. . It is now sporadic, now endemic, and occasionally both endemic and epidemic. It is sometimes inflammatory and sthenic; at other times typhoid and asthenic, at one time acute, and at another chronic. These differences are attended with essential differences in the nature of the disease, wo. o: only communicate to it different external asp. o ent on different internal conditions, but whi". “ totally different remedies. In the acute form of dysentery, ilation commonly tory, and when mild in character, off. The liquid precedes for some days the attack of do. to this state and frequent stools which at length s
when purely inflammaof constipation soon become streaked with blood; the griping pains which accompany the evacuations, and the straining and tenesmus which follow them, are often attended with distinct chills. The stools may be from eight or ten to sixteen or twenty in the twenty-four hours. The pulse is commonly quick and small, the tongue loaded, and the appetite little impaired. When the attack is more severe, it is generally attended at the very commencement with diarrhoea, often accompanied with nausea and vomiting, quickly "... scanty, mucous, or gelatinous stools, streaked with bl -, preceded by tormina, and followed by tenesmus. The pain in the course of the large intestines may be either severe, or it may not be urgent, but rather a sense of heat and aching than acute pain. Pain, however, is always induced by full pressure over the tract of the colon; and if, in any particular part of this tract, there be urgent pain, some degree of fulness may generally be perceived there. The progress of the disease is indicated by the increasing severity of all the symptoms, and more especially by the increasing frequency of the stools, by the increasing tormina and tenesmus, and the augmentation of the general febrile symptoms. It is not uncommon for from twenty to forty efforts at stool to be made in the twenty-four hours, with the effect of passing only a very small quantity of mucus and blood. In all cases the evacuations are exceedingly offensive; in the worst they are of a cadaverous odour, and the clots of blood are sometimes mixed with pieces of coagulated lymph or fibrin. In hot climates the disease is still more intense. The heat, the tormina, and the tenesmus, are more urgent and distressing; the thirst becomes excessive, the urine scanty or altogether suppressed, the stools slimy, streaked with blood, and attended with prolapsus ani, or watery and ichorous, “resembling the washings of raw beef, in which float particles or even large shreds of coagulable lymph, thrown off from the acutely-inflamed surface.” In these cases the prostration of strength is extreme, and is increased by most distressing and exhausting vomiting. When, as sometimes happens in this form of the disease, portions of the mucous coat of the intestine slough away, the countenance of the patient is sunk and cadaverous, and the odour of the stools, and in some degree, indeed, of the whole body, is putrid. In the asthenic form of dysentery, the tormina, tenesmus, and mucous and bloody stools are attended with great depression of all the organic functions, and extreme prostration of strength. The local dysenteric symptoms, exceedingly urgent from the commencement, are rapidly followed. by fever of a low nervous or typhoid type. This form of the disease often prevails as an epidemic; and under circumstances favourable to their accumulation and concentration, exhalations from the stools of the sick seem capable of producing dysentery in persons directly exposed to them, previously in a state of sound health. These forms of the disease are very apt to occur in hot seasons and in hot climates, where great numbers of persons are collected together in close and ill-ventilated apartments, in damp and unhealthy situations, as in barracks, garrisons, camps, crowded ships, &c. It is this form of dysentery which rages among the poor in seasons of scarcity, ...}. sometimes destroys whole armies in countries laid waste by war, and which so constantly, in besieged towns, anticipates the havoc of the sword. The duration of dysentery is as various as its types. It may prove fatal in a few days or hours, or last for weeks and even months, and ultimately destroy life by inflammation and gangrene of the bowels. In some cases the disease ceases spontaneously, the frequency of the stools, the griping and the tenesmus gradually diminishing, while natural stools return; but in other cases the disease with moderate symptoms continues long, and ends in protracted and exhausting diarrhoea. The causes which predispose to dysentery appear to be long-continued exposure to a high temperature, or alternations of heat and cold; hence the disease is generally most prevalent in summer or autumn, after considerable heats have prevailed for some time, and especially after very warm and at the same time very dry states of the weather. It is certainly more frequent, as well as much more severe, in hot than in cold or even in temperate climates. All observation and experience show that a powerful predisposition to the disease is formed by the habitual use of a high
and stimulating diet, and especially by indulgence in spi-
rituous liquors, by excessive fatigue; and by all causes which enfeeble the constitution in general, at the same time that they over excite the alimentary canal in particular. The exciting causes are long-continued exposure to intense heat, or to sudden and great alternations from heat to cold; exhalations from vegetable and animal matters in a state of decomposition, as from marsh, stagnant, river or sea water, from animalculae and minute insects, or from the flesh of deceased animals; noxious exhalations from the bodies of persons crowded together in close and confined situations, and more especially, as would appear, from the discharges from the bowels of persons labouring under dysentery; scanty and bad food, consisting more especially of vegetable or animal matter in a state of decay, as tainted meat, stale fish, unwholesome bread, unripe rice, rye, &c. The inflammatory affection of the mucous membrane of the large intestine in which dysentery essentially consists, passes, in the severe forms of the disease, into ulceration and even gangrene. On the examination of the large intestine in fatal cases after death, there is often found effusion of coagulable lymph, ulcers of various forms, and patches more or less extensive of mortification. In the most malignant varieties the internal surface of the whole alimentary canal is of a livid, purple, or dark colour, with patches of excoriation, ulceration, and gangrene. In the acute form of dysentery, when the fever is high, the pain intense, and the inflammation active, blood-letting from the arm is indispensable, which must be repeated to the subdual of the acute inflammatory symptoms. After a moderate general blood-letting, however, the local abstraction of blood by leeching or cupping is more efficacious; the number and the repetition of the leeches must of course depend on the urgency of the pain and the strength of the patient. The employment of purgative remedies in dysentery requires the greatest discrimination and caution. If the colon be distended with feculent matter which it cannot discharge, no remedies will succeed until this accumulation is removed; if, on the contrary, there have been already frequent and copious discharges of feculent matter, the administration of purgatives is absurd, for all purgatives are irritants, and the diseased membrane is already in a state of intense excitement. The practitioner should therefore carefully examine the state of the bowels with regard to their fullness or emptiness of faecal matter, and their actual state in this respect can almost always be ascertained with a great degree of certainty if due pains be taken to discover it. If there be reason to suppose that there is any accumulation of feces, the mildest purgatives should be given, of which the best is castor oil, and this should be cautiously repeated until the irritating matter is wholly removed. Great relief is at the same time afforded to the distressing tormina and tenesmus by emollient and opiate enemas injected in very small quantities. After the subdual of the inflammatory state by blood-letting, and the evacution of the accumulated faeces by mild purgatives, the great object is to soothe the irritated membrane by opiates, on the judicious employment of which, and the skilful combination and alternation of this class of remedies with mild purgatives, the successful treatment of ordinary dysente: y mainly depends. The acute forms of dysentery in hot climates require a prompt and decided combination of remedies, the best selection and administration of which it is impossible to discuss here. The asthenic forms with typhoid symptoms need a guarded yet active treatment, nearly the same as that which is proper to typhus fever with abdominal affection. [FEveR.] DYSPE'PSIA (Avarsilia, dyspépsia), Indigestion, the difficult and imperfect conversion of the food into nutriment. Digestion is a part of the great function of nutrition; its ultimate object is to convert the aliment into blood. Between the articles taken as food and the nutrient fluid of the body—the blood, there is no obvious analogy, and there is a wide difference in nature. Hence the function of digestion consists of a succession of stages, at each of which the food undergoes a specific change. Each change is effected by a peculiar process, for the accomplishment of which a special apparatus is provided. Of these processes the chief are mastication, deglutition, chymification, chylification, and faecation. The delicacy and complexity of the apparatus by which each of these processes is carried on has been already shown. [DIGESTIon.] The healthy condition and the natural action of every individual organ belonging to the portion of the
apparatus proper to each of these processes is necessary to the sound state of the function of digestion. It is easy therefore p see by how many causes it may be disturbed; in how many different organs the source of the disturbance may have its seat, of how varied a nature the disturbance may be, and how greatly the disturbance of the digestive function may derange the other functions of the body. In the history of the human family there is no known community of human beings in any country, and no age of human life, in which the first necessity of existence, that of taking food for the nourishment of the body, is not the cause of disease and death to great numbers, and of uneasiness, nay, sometimes even of intense. pain to far greater numbers. Why is this? Why is the digestive process more productive of suffering, disease, and death in man than in the lower animals of a similar structure, in which the function, considered in a physiological point of view, is scarcely at all less complex * The correct answer to this question would include a clear account of the causes of dyspepsia, and would suggest the appropriate remedies for the disease. Digestion being an organic function, when this function is healthfully performed, for reasons which have been fully developed, it is unattended with consciousness. The first effect of the disturbance of this function is to render the patient not only conscious, but painfully conscious, that he has a stomach. A sense of nausea, sometimes, when the
affection is severe, even vomiting, an obscure feeling of:
uneasiness, fulness, distension, weight in the region of the stomach, occasionally amounting to pain, and even severe pain, flatulence, eructation, a sensation of sinking, and lastly, a loss of appetite, constitute the train of uneasy sensations which, coming on after the reception of food, indicate disordered digestion, and which take the place of the feelings of refreshment and exhiliration which result from healthy digestion. When these uneasy sensations are occasioned by a disordered state of the stomach, it is easy to understand, from the exposition already given of the structure and function of this organ [Digestion], that the disorder may consist in a derangement either of its secreting arteries, or its mucous glands, or its organic nerves, or its muscular fibres, inducing a deficient secretion of the gastric juice, a deficient secretion of mucus, a diminished or increased irritability of the muscular fibres, by which the motions of the stomach are disturbed. If the gastric juice be deficient, the first step in the digestive process cannot take place, the food cannot be dissolved; if the mucus be excessive, the contact of the gastric juice with the food may be prevented : if the muscular fibres of the stomach are torpid or too irritable, the food may be detained too long or too short a time in the stomach. The causes of dyspepsia are either those which act directly and immediately upon the stomach itself, or those which act upon the whole body or upon particular parts of it, but which still affect the stomach principally and almost solely. Of the first kind are noxious, irritating, and indigestible substances taken into the stomach as articles of food or drink, such as tainted meat, decayed vegetables, unripe fruit, very acid matters, ardent spirits, &c.; and even wholesome food taken too frequently or in too large a quantity, especially when its nature is very nutritious, as when it consists principally of animal matter, or when a large quantity of nutriment is presented to the stomach in a very concentrated form, or is rendered too stimulating by being highly seasoned; the abuse of fermented and spirituous liquors, which is one of the most frequent causes of dyspepsia in its severest and most fatal forms; and large quantities of fluids, habitually taken at too high a temperature, as very hot tea, coffee, or soup. Of the second kind, or the causes which act upon the whole body or upon particular parts and functions of it, are —want of pure air ; hence the frequency of dyspepsia in large and crowded cities, and more especially in narrow and confined lanes and alleys, in the dirty and ill-ventilated houses of the poor. Want of exercise: from physical inactivity all the organs of the body languish, but the stomach first and most. Intense study or close application to business too long continued, implying both want of air and want of exercise. Mental emotion, more especially the depressing passions, fear, grief, vexation, dis
appointment, anxiety and hope deferred. Exposure to the influence of cold and moisture. In persons with weak stomachs and delicate skins, a cold damp day, more especially suddenly succeeding a hot day, often produces a severe attack of dyspepsia. Hence it is that dyspeptic complaints are so prevalent when cold and damp weather first sets in. Cold is a sedative to the nervous system, as heat is an excitant; and the depressing effects of cold seem to be peculiarly manifested in the nerves of the stomach. Excessive discharges from the body, as flooding, leucorrhoea, large bleedings from the arm, profuse and long-continued sweating, and above all protracted suckling. It is a common practice among the poor in this country to suckle their children too long. A feeble woman is often seen with a strong child at her breast a year and a half or two years old. The effect upon the constitution of the mother is most pernicious. Emaciation, sharpness of the features, with a peculiar expression in the countenance of languor and exhaustion, a sense of sinking at the pit of the stomach, dimness of sight, giddiness, spectra of different kinds dancing before the eyes, headache, with a small, quick, and sometimes almost imperceptible pulse, and total loss of appetite, are the peculiar characters of this variety of dyspepsia. The state of dyspepsia is most frequently a state merely of disordered function, without any appreciable change of structure in any of the tissues of the stomach. But all the symptoms of, dyspepsia are produced in their intensest degree when 'they arise from some organic disease of the stomach. Of these the most frequent is inflammation of its mucous coat. This inflammation may be either acute or subacute. When acute, the nature of the malady is indicated by characters so striking that it cannot be overlooked; but the subacute form often exists for a long period quite unsuspected, producing violent and obstinate dyspepsia, which is often greatly aggravated by the remedies employed to remove the complaint. The diagnostic sign of this form of the disease is tenderness on pressure in the epigastric region. In scirrhus of the pylorus and ulceration of the mucous glands of the stomach, organic disease not of unfrequent occurrence, there is superadded to the ordinary signs of ‘. a peculiar train of symptoms scarcely to be overlooked or mistaken. But dyspepsia is often the result of disease situated not in the stomach, but in some other organ. The stomach has been justly called the centre of sympathies, and there is scarcely any disorder of the body which does not affect the functions of the stomach in a greater or less degree. The organs the diseases of which are most apt to produce disorder of the stomach are the liver, the spleen, the uterus, the kidney, the bronchi, and the skin. In this secondary form of dyspepsia, the disease cannot be removed unless the seat of the primary affection, and the true nature of that affection, be ascertained. The stomach is the organ in which chymification is effected. Chylification is accomplished in the duodenum, and completed in the jejunum, ilium, and mesenteric glands; and the highly important part of the digestive process, that which consists in eliminating and carrying out of the system the non-nutrient portion of the aliment, is performed by the large intestines. Each of these organs may be the primary seat of disease, giving rise to the ordinary symptoms of dyspepsia; but to these there will generally be superadded peculiar signs pointing out the real seat of the malady, signs almost always to be observed if carefully looked for, and the detection of which is of the utmost importance in the treatment of the disease. The indications of cure are to avoid or remove the remote causes, to remove the symptoms which especially contribute to aggravate and continue the disease, and to restore the healthy tone of the disordered organs. There is no ". no class of medicines, no one mode of treatment capable of of dyspepsia when present, or of preventing its recurrence. This can only be done by a careful study of the exact cause of the disease in every individual case, and the precise seat and nature of the affection. The mode of treatment must be modified in strict accordance with these circumstances; and no mode of treatment will be attended with success of which the appropriate regulation of the diet and exercise does not form an essential part.
INDEX TO THE LETTER D.
Data, 1)atum, 313
Datüra Stramónium, 314
Dauphiné d'Auvergne, 316
D'Avenant, William, 316
David, Jacques Louis, 317
David's, St., 317
David's Day, St., 317
Davis, John, 318
Davis's Strait, 318
Davison, Secretary [Elizabeth]
Davy, Sir Humphry, 318
Dawes, Richard, 320
Day, Thomas, 320
Dead Sea, 321
Deaf and Dumb, 321
Debt, Action of 341
Debt, National [National Debt]
Decápoda sco vol. viii.
Deccan, 34 [p. 197]
Decimal Fractions [Fractions; Arithmetic] .
Decimal Notation tion; Arithmetic]
Decimal System of Weights and Measures [Weights and Measures]
Décius Mus, 343
Décius Trajánus, 343
Decker, Thomas, 343
Decker, Jeremias de, 343
Declination of the Magnetic Needle, 344