very unhealthy. This district was formerly part of the dominions of the rajah of Gurhwal, was overrun by the Goorkhas in 1803, and in 1815, during the Nepaul war, was invaded by the British, who suffered great loss here, and who, after the expulsion of the Goorkhas, kept possession of the territory.-DEYRA, the principal town of the district, is situated in the midst of dense mango groves, at the intersection of 2 routes of trade, 2,369 feet above the sea.

DEZFOOL, DEZFUL, or DezPHOUL, a city of Persia, in the province of Khoozistan, on the eastern bank of a river of the same name; pop. estimated at 15,000. It is the principal mart of the province, and has a fine bridge of 22 arches, said to have been built by command of the celebrated Sapor. About 10 miles S. W. from the city are mounds of ruins which cover the site of the ancient city of Susa.

D'HILLIERS. See BARAGUAY D'HILLIERS. DIABETES, GLUCOSURIA, DIABETES MELLITUS, GLUCOHEMIA (Gr. diaßaivo, to pass through), a disease characterized by an excessive secretion of saccharine urine. Though disease marked by diuresis and attended with wasting of the body was frequently spoken of by earlier authors, Willis (1659) was the first who noted the distinctive character of the complaint, the presence of sugar in that fluid. Since his time diabetes, which is not a very rare complaint, has been frequently made a subject of study, yet still a great deal of obscurity envelops its causes, its essential character, and its treatment. The invasion of diabetes is commonly insidious. The attention of the patient is perhaps first attracted by the quantity of urine he passes and by the frequent calls to void it, or he notices that while his appetite is greatly increased he is growing weaker and thinner. If the urine be now examined, it is found to be not only greatly increased in quantity, but somewhat changed in appearance; it is paler, transparent when first passed, and assumes on standing an opalescent tint like the whey of milk or a solution of honey in water. It has no odor, or a somewhat aromatic one, compared by some to that of new-made hay, by Dr. Watson to that of a room in which apples have been kept. If kept for a few days at a moderately elevated temperature, instead of acquiring an ammoniacal odor like ordinary urine, it has a sharp vinous smell, and will be found to be acid rather than alkaline. The urine has commonly a decidedly sweet taste; drops of it upon the patient's linen or clothes stiffen them like starch, and sometimes leave on evaporation a powdery efflorescence. The specific gravity of the urine is greatly augmented; instead of being from 1.015 to 1.020, as is commonly the case, it ranges from 1.025 to 1.050; M. Bouchardat reports it even as high as 1.074. Two or three simple and easily applied tests are sufficient to render the presence of sugar certain. In what is called Trommer's test, a drop or two of the solution of the sul phate of copper is added to a little of the urine in a test tube; a solution of caustic potash is

now added in excess, and the mixture gently boiled over a spirit lamp for a few minutes; if sugar is present, a precipitate of a reddish or yellowish brown (suboxide of copper) will be thrown down, otherwise the precipitate will be black (common oxide). In Moore's test, a little of the suspected urine is mixed in a test tube with about its volume of liquor potassæ, and the mixture boiled for 5 minutes; if sugar be present, the fluid will acquire a brown hue, otherwise it remains unchanged. A 3d test is founded on the fact that diabetic urine rapidly undergoes fermentation when mixed with a little yeast and kept in a warm place. The sugar to which diabetic urine owes its peculiar properties exists in the form of glucose or grape sugar. This is present in all proportions, from a mere trace to 30, 50, and even 134 parts in 1,000. The quantity of solid matter thus drained from the system is very great; Dr. Thomas Watson estimates it on the average at 14 lbs. per day, but it sometimes amounts to many times this quantity; and it is this drain of solid matter, together with the large amount of urine passed, which gives rise to the constant thirst and the enormous appetite of diabetic patients. Early in the disease, as was before observed, the symptoms are not well marked; when the complaint is established, and the large excretion of urine begins to attract attention, the patient complains that despite his excessive appetite he grows thinner and weaker; the mouth is pasty, the skin dry and hard, the bowels constipated. The digestive functions, at first normal, become deranged; the patient is troubled with heartburn, with a feeling of weight and pain in the epigastrium, sometimes with vomiting. The strength declines, the patient becomes emaciated, the generative functions are impaired or lost; vision often becomes dim, the gums are spongy, there is tenderness and swelling about the orifice of the urethra, the memory and intellect fail, and the temper becomes irritable. In the course of the disease pulmonary consumption is very apt to supervene and carry off the patient. Toward the last, diarrhoea, fetid breath, effusion into the great cavities, and oedema of the extremities, precede death. Diabetes is essentially a chronic disease, lasting often many years; it is also an obstinate and intractable one, although most of the cases seem benefited by treatment, and sometimes it would appear to be completely cured.-Treatment. In the beginning of the present century Dr. Rollo found that the amount of urine in diabetic patients as well as its sweetness was very much diminished by confining them to an animal diet. When the ready conversion of starch into grape sugar became known, this was assumed to be the origin of the sugar, and the benefit derived from an exclusively animal diet was thus explained. Unfortunately, few patients have the resolution to restrict themselves for any length of time to such a diet, and even when persevered in it is found to be merely palliative. The experiments of C. Bernard have thrown a new light

upon the subject. He has ascertained that sugar is a normal secretion of the liver in all classes of animals, carnivorous as well as herbivorous; that it takes place in the liver of the foetus as well as in that of the adult; that irritating the origin of the 8th pair of nerves in the 4th ventricle increases the secretion of sugar, producing an artificial diabetes. In a state of health the normal secretion of sugar poured into the circulation by the hepatic veins is rapidly decomposed and excreted by the lungs; when the amount is increased by disease, the excess passes off by the kidneys. Under the influence of diastase, sugar is likewise formed from the starch of the food in the process of digestion, as a necessary preliminary to its absorption. When diabetic patients are placed upon an animal diet, this source of supply is cut off, and the amount of sugar in the urine is diminished, but it is still present, since the liver keeps up the supply. M. Mialhe, influenced by the theoretic belief that sugar in the course of the circulation is decomposed under the influence of the alkalinity of the blood, and that in diabetes the blood is deficient in alkalinity either positively or relatively to the amount of sugar contained in it, recommends the use of the bicarbonate of soda in large doses. He recommends a dram to be taken 3 times a day, morning, noon, and night; this is gradually increased until from 180 to 270 grains are taken in the course of the day. In addition, the patient is directed to take Vichy water with his meals, and is recommended to drink lime water to the extent of 2 or 3 pints daily. He is permitted to indulge in the ordinary variety in his diet, but the quantity of farinacea is reduced or at least Flannel is ordered to be worn next the skin; the vapor bath is administered 2 or 3 times a week. By these means M. Mialhe reports a number of cases to have been cured. Dr. A. Clark of New York (New York "Medical and Surgical Journal," Jan. 1859) reports several cases of diabetes either cured or greatly benefited by the use of bicarbonate of soda and of blisters to the nape of the neck. Dr. Clark administered the soda in doses of 11 grains, to be taken as frequently as could be borne until the urine was rendered alkaline or the stomach was nauseated. Beside the alkaline treatment, the means principally relied on have been restrict ing the quantity of farinaceous matter in the patient's diet as far as possible, indulging him in watery vegetables (spinach, turnips, cabbage, &c.) rather than in bread or potatoes, and the use of opium. This last remedy allays the nervous irritability of the patient, and diminishes the thirst and the amount of the urinary secretion.

DIAGNOSIS (Gr. diayvwois, examination, decision), a term in medicine indicating that department of pathology whose object is the distinguishing of diseases by the knowledge of their special pathognomonic signs. To distinguish a disease under all its various forms, and when complicated by symptoms of other affections, is

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of the first importance in practical medicine, and requires all the acuteness and discrimination of the physician; without a correct diagnosis, treatment must be empirical and hazardous. A mere acquaintance with the symptoms of each disease cannot enable the physician to make his diagnosis. These symptoms are given briefly under the different diseases; diagnosis will be treated here only as a branch of general pathology. Of the symptoms of disease, some are characteristic and pathognomonic, essential and always present; some are common to other diseases, and are of value only when taken in connection with the former class. Examples of the former are the eruptions of the exanthemata, and the mobility of the ends of broken bones; of the latter, the increased frequency of the pulse, heat of the skin, and thirst, common to many different diseased states. A physician must know how to examine and interrogate a patient, to use his own senses of sight, hearing, and touch, to sift the statements of attendants, to weigh justly positive and negative signs; which he can only learn by a knowledge of anatomy and pathology, by experience at the bedside, by an acquaintance with the physiological functions of organs, and by familiarity with the physical examinations of the sick. His fingers must be educated to a sensibility equal to that of the blind man's; his ear, armed with the stethoscope, must hear the first footsteps of disease in the heart and lungs, or the first murmur of life in the gravid uterus; his eyes, assisted by the microscope, must follow the course of morbid growths back even into the primary structure of the cell; he must press, percuss, and measure with the greatest delicacy and exactness; he must be familiar with chemical reactions, in order to detect and neutralize poisons, and arrest the formation of dangerous precipitates in the nutrient and excrementitious fluids. By this manner of interrogating and examining, both by physical and rational signs, every organ and function, the seat, extent, and nature of the disease are ascertained; and it is in making a diagnosis, more than in the treatment, that one physician excels another; for though a blind exhibition of remedies may occasionally be successful in arresting disease, it must be obvious to every reasoning mind that a knowledge of the disease is the first and great essential to its rational treatment. There are many causes which render the diagnosis of disease difficult and uncertain-such as the advanced stage at which many affections are seen; the unusual predominance of certain merely sympathetic phenomena, which mask the primary lesion; the occurrence of new and anomalous types of disease; the complication with other diseases; and the tender age, imbecility, insanity, dissimulation, and deceit of patients. It must be evident from this, what a union of rare faculties and varied acquirements is necessary to enable a physician to make a correct diagnosis of disease; and also that, without this primary result, all speculation as to its progress and termination is mere con

jecture, and all treatment blind and base empiricism. The French school of medicine is famous for the stress it lays on diagnosis; and students from other parts of Europe, and more especially from the United States, flock to Paris to acquire the elements and practice of this most essential branch of their profession.

DIAGORAS OF MELOS, surnamed the Atheist, a Greek philosopher, lived in the time of Socrates and Aristophanes, but neither the date of his birth nor that of his death is known. He must have removed from his native island to Athens before the performance of the "Clouds " of Aristophanes (424 B.C.), for he is alluded to in that piece as one well known to the Athenians. He was a disciple of Democritus of Abdera. He ridiculed the popular religion, and attacked especially the Eleusinian mysteries, on account of which he was accused of impiety (411 B. C.). Fearing the result of a trial, he made his escape from the city. He was condemned to death by the court, and a price set upon his head. Notwithstanding this, after living for a time at Pallene, he finally died at peace in Corinth. His works are all lost.

DIAL. Sun dials are among the most ancient of human inventions, and, although sometimes said to have been invented in Lacedæmon, were more probably derived by the Greeks from eastern nations. The dial of Ahaz, the king of Judah, is one of the earliest mentioned in the history of the East, and it is probable that the Jews learned the use of this invention from the Babylonians. According to Wilkinson, "there are no indications in the sculptures to prove the epoch when the dial was first known in Egypt." The modern improvements in artificial modes of measuring time are so great, that sun dials are now more a matter of curiosity than of use. They may be divided into 2 essentially different kinds, one of which we may call geometrical, the other algebraical. In order to comprehend the first, we need only observe, that if a rod or gnomon be placed parallel to the axis of the earth, its shadow, conceived of as a sheet of darkness passing in a plane from the rod on the opposite side of the sun, would swing steadily and equally round the rod as a hinge, so long as the sun shone upon it. Upon whatever surface this shadow fell, whether horizontal, vertical, or inclined, its place could be used as a means of measuring time. And if upon this surface lines were drawn, marking the place of the shadow at definite hours of the day, the rod might be made as short as we pleased, reduced indeed to a single ball, held in the place where the extremity of the rod had been, and the shadow of this ball would mark the time upon the lines of the shadow of the rod. The other sort of dial, the algebraical, is more difficult to explain without the use of a diagram. It is drawn upon a piece of card, to which is attached a plumb line with a bead sliding upon it; the card being held in such a manner that the upper edge shall point at the sun, its plane being vertical, the bead marks the

hour upon the face of the card. This dial has the advantage of being portable. Dials of the first kind, of a rude nature, may be made portable by having the rod and the dial surface light enough to be balanced upon a compass needle. Beautifully engraved sun dials, for the regulating of clocks, are manufactured by the electrotype process in copper.-The term dial is also applied to any graduated surface, such as a clock or watch face, upon which time is marked out.

DIALLAGE (Gr. diadλayn, change, alteration), a mineral of the augite family, so named from its tendency to cleave in different directions. It is a variety of hornblende, in thin foliæ, of various shades of green, gray, brown, and bronze colors, and is found in serpentine and greenstone. Its specific gravity is 3.25. Diallage rock, also called euphotide, is a compound rock of diallage and feldspar.

DIAMAGNETISM. In the native magnet (an ore of iron) a peculiar force resides, which, if a mass of this body be suspended freely, turns or directs it into a line varying slightly from the course of a meridian on the earth's surface. The same end of the magnet being always directed toward the north, this has been termed its N. pole; the opposite, its S. pole. Certain bodies, especially iron, brought near to a magnet, have the magnetic condition induced in them, the extremity nearest either magnetic pole becoming a pole of the opposite name, that most remote a pole of the same name. This result is in accordance with the law that like poles repel, while unlike attract each other. A soft iron bar, around which the electrical current is made to circulate upon a coiled conductor, or helix, becomes magnetic for the time, but loses its magnetism when the current ceases. Small magnetizable particles, as iron filings, dusted upon a surface on which a magnet rests, or agitated near it, become arranged in lines which, between unlike poles that are presented to each other, run across in straight lines, while about these on either side they form curves, making larger and larger sweeps into space. The lines thus indicated have been named inagnetic curves, or lines of force. Until recently, the number of magnetic bodies was supposed to be very small. Becquerel, in 1827, found that a needle of wood playing freely on a pivot took a direction across, not in, the magnetic curves; and in 1829 Le Bailli also observed that bismuth repelled the magnetic needle. But the significance of these facts was not understood until an accidental discovery of Faraday, in 1845, led that philosopher into a full investigation of the phenomenon. In the course of his experiments on magnetic rotary polarization, he observed that a bar of so-called "heavy glass," suspended between the poles of an electro-magnet, moved, as soon as by the passage of the electrical current magnetism was induced in the latter, into a position crossing the lines of force, or at right angles to the line joining the poles. Terming the position assumed by a soft iron bar which is lengthwise between the two poles,

DIAMAGNETISM

or from one to the other, axial, Faraday gave to the new direction assumed by the glass the name of equatorial. The glass was not merely thus directed, it was repelled by either pole; and if, reduced to the form of a small mass or cube, it was thrown out of the line joining the poles to one side or the other, it moved into the position of weakest magnetic action. This new-found property of certain bodies Faraday termed diamagnetism; and in contrast with this, he denominated the familiar form of magnetic action paramagnetism. His experiments warrant the conclusion that, with a sufficiently powerful electro-magnet, all substances whatever can be shown to exhibit one or other of these properties. Liquids and solutions were examined by being suspended in glass vials, the known influence of the glass being allowed for. Among paramagnetic substances, by far the most powerful is iron, then nickel and cobalt, and, in a slight degree, manganese, palladium, crown glass, platinum, osmium, and some others. Vacuum serves as zero in the scale. Then, passing from the less fo the more diamagnetic bodies, are found arsenic, ether, alcohol, gold, water, mercury, flint glass, tin, heavy glass, antimony, phosphorus, and, by far the most powerful, bismuth. Flames are diamagnetic, being so strongly repelled by the poles that they divide and pass up on either side, a descending current of air going down in the middle. Most organic substances are diamagnetic; wood, starch, sugar, leather, bread, and even animal tissues and blood, are instances. Oxygen, and perhaps nitrous gas, are the only gases which are known to be ordinarily magnetic; and when it is added that oxygen loses in a degree, though not wholly, its magnetic condition by increase of temperature, it will be seen that the properties of this constituent of our atmosphere probably have important bearings on the production of terrestrial magnetism. Green glass is magnetic in consequence of the iron it contains; and to render wood ordinarily magnetic, it is only necessary to cut a chip of it with a common knife. The magnetic condition of any compound body is found to be determined by what may be called the algebraic sum of the magnetic and diamagnetic powers of its constituents. Thus a compound or solution containing much iron will always be paramagnetic in greater or less degree; but if the iron be blended with comparatively large amounts of water and other diamagnetics, it may be brought to the neutral point, or the compound may be actually diamagnetic. Under all ordinary circumstances, the decidedly magnetic or diamagnetic bodies give to combinations their own character. Another important point is the influence of enveloping material. Certain substances that are repelled, and take the equatorial position in air, are attracted and set axially in water; and even a solution of iron, magnetic in air, if weaker than another solution in which it is immersed, will stand equatorially, and act as a diamagnetic. In terming a body magnetic

or diamagnetic, then, we mean that it is such with reference to the medium in which it is tried; and as this medium is commonly air, in which the magnetism of the oxygen dominates over the opposite property of the nitrogen, it is evident that some so-called diamagnetics are only relatively such. With reference to the theory, Faraday now considers that the diamagnet is not rendered polar, as is the magnet, but simply repelled. Prof. W. Thomson has supposed the diamagnet to be simply a body less magnetizable than air, but still polar. In this case it would move away for the more magnetic air, just as in gravitation smoke makes way and ascends above the more strongly gravitating cold air. Plücker, Tyndall, and others adhere to a modified form of Prof. Faraday's earlier view, namely, that the diamagnet is a body susceptible in greater or less degree of a double polarity opposite in character to the double polarity of the magnet; or, in the language of Ampère's theory, that as the currents induced in soft iron are parallel to the currents in the inducing magnet or battery wire, so, in bismuth and other diamagnetics, the currents are induced in contrary directions, so that these bodies become inverted magnets, and place themselves across the magnetic lines of force.

DIAMANTINA, formerly TEJUCO, a city of Brazil, and capital of the diamond district, situated in a valley of the province of Minas Geraes, at an elevation of 5,700 feet above the sea; lat. 18° 28' S., long. 43° 50′ W.; pop. about 6,000. It is built in the form of an amphitheatre, with wide, ill-paved streets, and handsome churches, one of which, belonging to negroes from the coast of Africa, contains an image of a black Virgin. Most of the houses are surrounded by pleasant gardens, and the environs of the city are adorned with orange and banana trees. The climate is mild. The inhabitants are employed chiefly in the gold or diamond trade.

DIAMETER, a straight line passing through the centre of a circle, terminated at each end by the circumference. Straight lines holding an analogous relation to curves, such as the conic sections, are also called diameters of those curves.

DIAMOND (from adamant, and this from Gr. a privative and daμaw, to subdue), so named on account of its extreme hardness and indestructibility, a gem distinguished above all other precious stones for its brilliant lustre and hardness. It is met with in solid pieces of small size in alluvial deposits which are worked for gold. In a few instances diamonds have been found attached to loose pieces of brown hematite, and one was discovered in a kind of conglomerate rock, composed of rounded silicious pebbles, quartz, and chalcedony, cemented together by ferruginous clay; but no positive knowledge is had of the particular rock in which they originated, more than that it is one of those belonging to the metamorphic group, which yield gold. In the districts where they occur, a peculiar variety of light yellowish and white quartz rock, of laminated structure, called itacolumite,