of the flat part are filed or ground to size, and the ticularly in wrought-iron or steel. In this drill the drill is then rotated with the chuck and straightened body is cylindrical for a distance of from three to six until the axes of the two coincide. It is then har- diameters from the point, and has but one groove and dened and tempered to the right degree for a short one cutting-edge. The groove has straight sides at an distance at the point, and is complete except the cut-angle of from 90° to 120° with each other, and is ting-edges. Many modifications of this style of body made by first drilling a hole of small diameter, but of are in use, depending on the purposes intended and considerable length, along the axis of the cylinder, and the tastes of the makers; but such frequent re-dress- milling the groove to this hole. The end of the cylinings are required to maintain the standard size that der is turned conical, with the included angle about it probably costs more in the end than the more com- 140°, and, after the groove is made, is ground or filed plete and finished forms to be described hereafter. with a clearance from the cutting-edge in the form of Forged drills are sometimes made by drawing down a spiral of an angle of from 3° to 5°. In using this the body to a flat somewhat narrower than the size of drill a hole of slight depth, but of the exact size and the drill, and extending from the shank to the point, central with the axis of rotation, is first made, and, and then twisting this flat into a spiral for its entire the drill being started in this hole, will follow a length. remarkably straight path, being guided entirely by the fit of its short cylindrical body. Beyond this part of the body, with its groove, the remainder is of smaller diameter, to make room for the chips or cuttings, and to permit the ready introduction of lubricants. There are several other special forms of bodies of drills, the limited use of which renders it unnecessary to enumerate them.

are such as to make their production a difficult matter, | by no means attractive white flowers. The leaves form particularly if ground by hand. Unless both cutting- a rosette around the base of the flower-stalks, and are edges are precisely the same, not only in length, but about two inches long, formed of a narrow, flattened also in the angle made with the axis and in the kind leaf-stalk, and with a broad, two-lobed lamina at the and amount of clearance, the size and form of the hole apex. This blade is somewhat thick and fleshy, and drilled will not be reliable. The difficulty of correctly is furnished with long tapering ciliæ or teeth. When grinding twist-drills by hand is greater than that of an insect or any substance falls on this fleshy face the fat drills, and this at one time threatened to be a lobes instantly close and capture whatever may have serious obstacle to the general introduction of the excited them. The name "flytrap" is derived from former. The invention of drill-grinding machines has this behavior. It is singular that the history of the gradually and progressively overcome the difficulties discovery of this remarkable plant should be unknown. of the case, until there is now a machine which will Mr. William Canby, in an able paper contributed to the grind the cutting-edges of drills of any kind or size, Gardener's Monthly, August, 1868, remarks: "It was within its capacity, in a theoretically perfect manner. discovered about one hundred years since, probably by In this machine the drill is held by the two opposite John Bartram, as Ellis, the English naturalist, who first corners of the cutting-edges and by the centre at the brought the plant into notice and gave it its botanical end of the shank; so that, after grinding one edge, name, states in his letter to Linnæus that in 1765 his the drill can be turned over and the other edge ground friend Peter Collinson had given him a dried specimen of the same length, angle, and clearance, regardless of which he had received from Bartram." But Sir James any crookedness or imperfection in the body. The Smith (Selections of the Correspondence of Linnaus, mechanism which holds the drill is contained in a vols. i. and ii.) states that "the Dionaa was first frame which can be partially rotated about an axis at brought to this country in the summer of 1768 by an angle with the flat face of a grinding-wheel, so that Mr. Young, gardener to the queen; and Mr. Ellis the surface ground will be that of a cone about this described it, and had a drawing and a plate engraved axis. The axis of the drill does not coincide with this from a plant which flowered in his chambers the folaxis, but bears such a relationship to it that the con- lowing August. It was from this plate and his characical surface has the proper eccentricity. The relation- ters of the plant that Linnæus's description was drawn ship between these two axes adjusts itself automatically up for his Mantissa." Little is known of Young's travels. to suit the diameter of the drill being ground. Drills From a note in The American Handbook of Ornamental ground on a machine of this kind can be depended on Trees, p. 117, it appears he was known in America as the to make holes of uniform size with a minimum ex- "king's botanist," that he was regarded as a sort of penditure of power and waste of drill. rival to John Bartram, and owned a place contiguous to Bartram's near Philadelphia, on which he planted a few trees, some of which survived to be referred to in the work cited. William Bartram, in his Travels, published in 1791, says. referring to Dimaa: “This wonderful plant seems to be distinguished in the creation by the Author of Nature with faculties eminently superior to every other vegetable production; specimens of it were first communicated to the curious of the Old World by John Bartram, the American botanist and traveller, who contributed as much if not more than any other man towards enriching the North American botanical nomenclature, as well as its natural history. It may be Bartram sent the dried, and Young carried the living, plants. It has been a question whether the plant derives any benefit from the insects caught. Kirby and Spence (Introduction to Entomology (1818), vol. i. p. 295) give the experiments of "a gardener, Mr. Knight," who put raw beef on the leaves, and the plant was more luxuriant than others not so treated. This Mr. Knight was afterwards the founder of the celebrated nurseries of Knight & Perry of Chelsea, often referred to in Mr. London's works. The same experiment was tried by Mr. Wm. Canby in 1868, and reported in the magazine already cited, and with like results. Mr. Darwin (Insectivorous Plants, ch. xiii, p. 301, Am. ed.) tried a few experiments on Dionaea, which were amply sufficient to prove that it [the leaf] digests." Mr. Peter Henderson, a well-known plant-grower of New York. published an account of some experiments differing from these conclusions, but the general belief is that the plant actually eats the insects it captures.

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Drilling Machines, in which are used the drills already considered, are of various designs, the essential features being a strong stiff spindle to hold the drill a means of rotating this spindle at varying speeds to suit the different sizes of drills and with sufficient force to make the drill cut the metal; a means of traversing this spindle lengthwise, during the rotation, to maintain the proper amount of cut for each revolution; a means of varying this traverse or feed to suit the character of the material being drilled; and a means of firmly holding the work in the best manner to resist the thrust and the torsional strain of the cut, and to adjust it to the desired position. The various forms of drill used in boring stone are described in the article ROCK DRILL.

DROSERACEÆ. In this natural order of plants are found the remarkable "Venus's flytrap," Dionaea muscipula, and the no less curious and interesting genus Drosera, or the "sundew." The order has been a difficult one to understand in regard to its relation to other orders of plants. Dr. Lindley in his arrangement places it in his Berberidal alliance, and suggests a relationship with grapes and fumitories; Professor Asa Gray places it between violets and rock-roses on the one side and St. John's worts on the other. The order Droseracea, as defined by Prof. Gray, consists of bog-herbs, mostly glandular-haired, with regular hypogynous flowers, pentamerous and withering; persistent calyx, corolla, and stamens, the anthers fixed by their middle and turned outward; and a one-celled pod, with twice as many styles or stigmas as there are parietal placenta. The leaves are circinate in the bud; that is, rolled up from the apex to the base, as in ferns. There are but seven genera in the order-Drosera, Aldrovanda, Dionæa, Byblis, Drosophyllum, Roridula, and Sondera-found by some representative in North and South America, Europe, Cape of Good Hope, Madagascar, New Holland, China, and the East Indies, generally in bogs and morasses or in moist, sandy places. Of these, only the three first named have found a place in popular literature, but the history of Drosera, and Dionaa particularly, has been one of great interest.

The Dionaea, or Venus's flytrap, is found only in North Carolina, in one comparatively limited area. It is an acaulescent plant, sending up a flower-stalk of from two to four inches high, and having comparatively small and

The sundews, species of Drosera, are also famous in connection with the history of insectivorous plants. They are small perennial plants, sometimes tufted, at other times branching, with the flowers ranged on one side of a short scape; and with the glands, which usually cover the whole plant, but especially the leaves, exuding drops of viscid liquid. It is from this fact that the name Drosera is derived, the Greek droseros signifying dewv. Unlike the other representative of the order Dioned, which is limited to so small an area, droseras are found in most of the temperate regions of the earth, and some of the individual species are common alike to Europe and America. Over one hundred species have been described, but the genus is variable, and many species will probably be reduced to mere varieties. The specics

of the United States are D. Anglica, D. brevifolia, D. popularity. He also published several historical incapillaris, D. filiformis, D. rotundifolia, D. linearis, vestigations and essays. These were chiefly preliminary and D. intermedia. Of these, D. Anglica and D. ro- to his great work, Geschichte der preussischen Politik tundifolia not only grow in the Atlantic United States, (5 vols., 1855-81). In these, from original sources as well as in Europe, but are also found on the Pacific previously unused, he sets forth fully the development coast; D. brevifolia and D. capillaris are confined to of Prussia which has resulted in the formation of the the South and South-west; D. linearis and D. inter- present German Empire. Among his other writings media are Northern species; and the curious D. fili-are-Das Testament des Grossen Kurfürsten (Leipsic, formis is found only along the sea-coast from Massa- 1866), Grundriss der Historik (1868; 3d ed., 1882), and chusetts to Florida. Gustav Adolf (1870). Under his editorial care many documents relating to the history of Frederick the Great were published. In his later years he resumed his investigations of Greek history, and issued some valuable dissertations. Throughout his career he was noted for his elegant style in speaking and writing, and for his persuasive and enthusiastic eloquence. DRUPACEÆ. This is a name suggested by De Candolle, and adopted by Lindley, for a distinct natural order of plants to include the almond, peach, cherry, and plum, as distinct from the order Rosacea, defined by other botanists. In like manner he adopts Pomaceae to cover the apple, pear, quince, and a few allied genera, while for Rosacea proper he reserves such plants as the rose, blackberry, raspberry, strawberry, cinquefoil, spiræa, and similar plants. A drupe is a fruit with one or two stones with kernels, which fruit, when ripening, has the outer portion of the pericarp fleshy; and it may be readily seen how the order Drupacea suggested itself for the plants named. The peach, however, not unfrequently has flowers with four, or even five, carpels, which they often will perfect. This is seen very often in the case of the semi-double flowered varieties. Again, the almond has a comparatively dry fruit. Dr. Asa Gray does not regard the distinction as of more than sectional value. He places all these plants under one order, Rosacea, subdividing it into Amygdala, Rosaceae, and Pomacea. Drupaceœ of some authors will therefore come under Dr. Gray's sub-order Amygdala.

The chief interest attaches to their insect-catching and insect-eating proclivities, which have been so clearly made manifest by Charles Darwin's famous work on Insectivorous Plants. That the viscid glands are means by which the plant captures insects and uses them for food was suspected before Charles Darwin undertook the proof of it. His grandfather, Erasmus Darwin, supposed these glands were for the purpose of preventing small insects from infesting the leaves, but he adds, "Mr. Wheatley, an eminent surgeon in Cateaton Street, London, observed these leaves to bend upward when an insect settled on them, like the leaves of the Muscipula veneris (Venus's flytrap), and pointing all their globules of mucus to the centre-that they completely entangled and destroyed it" (Botanic Garden, canto i., note to line 230). It is remarkable that, so far as it appears from Mr. Charles Darwin's elaborate work on the Drosera, he had wholly overlooked this observation of his grandfather made three-quarters of a century before, which his own experiments tended so remarkably to confirm. The great practical value of Mr. Darwin's researches in Drosera is that he shows that the viscid glands of plants have a use never before suspected-namely, that of absorbing for the use of the plant nitrogen from the atmosphere, instead of by the roots solely, as had been the belief hitherto. Darwin's observations have been confirmed by observers in America, Mrs. Mary Treat of Vineland, N. J., having shown that the long, slenderleaved species of that section coils back over an insect when caught till it looks like the uncoiled frond of a fern. Dr. Hooker has found in an Australian species an attempt to form an appendage as in Dionaea, from which it may be inferred that the latter is a development from a Droseraceous parent. (T. M.)

DROYSEN, JOHANN GUSTAV (1808-1884), a German historian, was born at Treptow, July 6, 1808. He graduated at Berlin, and became in 1829 a teacher in a gymnasium, in 1833 a private lecturer, and in 1835 a professor extraordinarius. In 1840 he was appointed professor of history at Kiel, where he soon took an active part on the German side in the Schleswig-Holstein controversy. He assisted in composing the Staats und Erbrecht des Herzogthums Schleswig (Kiel, 1846), and the Aktenmässige Geschichte der dänischen Politik (Hamburg, 1850). He was a representative of the provisional government of the duchies in the German Diet at Frankfort, and was afterward elected to the National Assembly. In 1851 he accepted a call as professor in the University of Jena, and devoted himself to historical studies. In 1859 he became professor in the University of Berlin, where he remained till his death, June 19, 1884.

Droysen's literary career was remarkable for its variety and productiveness. His first work, a translation of Eschylus, was published in 1832, and reached its third edition in 1868, while his translation of Aristophanes, published in 1836, reached its second edition in 1871. They are the standard German translations of these authors. Continuing his labors in ancient literature, he prepared a History of Alexander the Great (1833), a History of Hellenism (1836-43), and several essays on Greek subjects. While at Kiel, besides some political works written in company with others, he published lectures on the History of the War for Freedom (1846). While at Jena he published an excellent Life of Field-marshal York of Wartenburg (Berlin, 1851; 8th ed., 1878), which obtained great

It is worthy of note that while the order Rosacea in general is wholly free from noxious qualities, the Drupaceous section is in many respects poisonous. The leaves and kernels yield large quantities of hydrocyanic acid. In a case known to the writer peachleaves were fed one evening to several rabbits, which were all found dead the next morning. Oil of bitter almonds is a deadly poison, and prussic acid is abundant in peach-kernels. It is remarkable therefore that the flesh around the stones is always very wholesome.

(T. M.)

DUALISM. Dualism may be viewed as either (1) an ontological principle, or (2) a psychological assumption, or (3) a moral theory in practical philosophy.

I. Moral Dualism is grounded in a metaphysical principle (unconsciously assumed,) but it is of so great antiquity, and through religious sects has exerted so marked an influence on the progress of thought, that it will be convenient to consider it in the first place.

Parseism is, perhaps, the most thorough practical dualism, of ethical and religious content, of which we have any record; through Gnosticism and Manicheism it may be traced into the Middle Ages (e. g., the Albigenses; see Mosheim, 10th and 11th Cent.), if it be not even recognizable in sects and opinions of our own day.

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The earliest distinct form of it is found in the Avesta, ascribed to Zoroaster (6th Cent. B. C.). In the first Fargard," Ahura-Mazda (Ormuzd) speaks to holy Zarathustra (Zoroaster), recounting his creations, and opposing them to the creations of Angro-Mainyus (Ahriman) which he made through the Devas. The first created fertile lands, useful animals, summer, fire, light, and all good things; the other made deserts and winter, cattle-destroying wasps, injurious insects and devouring beasts, evil thoughts, unbelief, sloth, poverty, worship of idols, uncleanness, murder, the burning of the dead, and burying of corpses, plagues, war, pillage, snow, and earthquakes.

Here is already intimated that there are two eternal | who had captured a portion of the light, and marriage sources of good and of evil. Ormuzd is (figuratively) is his device for perpetuating his sway. pure infinite light, creator of all that is good. His symbol is fire, and fire-worship is the ritual way of approaching and adoring him. Ahriman is the opposite of all this-impure darkness, the source of all evil. The dualism, as we observe, extends through all moral and physical nature, the soul, and the universe. Souls are created by Ormuzd, but, in leaving heaven, their native place, and entering earthly bodies, the struggle with Ahriman begins. This dualism is a simple and natural explanation of the existing and perplexing antinomies of the world and of human life. (See J. S. Mill, Essays on Religion, I.) If a subtle metaphysics attempted to reduce this dualism to monism, by the emanation of both Ormuzd and Ahriman from an undefinable first principle, or, the decline of Ahriman from good, this must be regarded as later, and it was of no permanent influence or value.

Persian influence may be recognized in early Chris tian sects, and most notably among the Manichees. The Gnostics, at Alexandria, Antioch, etc., in the time of Hadrian and succeeding emperors, show the results of a crude syncretism of Greek Philosophy, Christianity, and Persian dualism. Saturninus, Basilides, Marcion, Valentinus, etc., through all their fantastic forms of "Gnosis," agree in their practical, ethical dualism of God and Matter. The first-begotten emanation from Deity had only the semblance of humanity, and could not really suffer death upon a cross. For the material world is evil, and nature itself is the evil principle standing over against spirit and what is good in complete opposition. It follows that the flesh of man is the home of this evil, and hence comes a perpetual struggle between the spirit of man which is an emanation from the realm of light, and its corrupted material tabernacle. Emancipation by death, or by a stern asceticism, alone releases the soul from its bondage. Marriage is Satan's work. Only the souls of men are immortal; the body perishes forever.

Manicheism was a more consistent dualism, linked more directly with that of Persia, and of wider and more permanent influence. We know it best through the eloquent St. Augustine, at first a disciple, and then an earnest opponent, but extracting freely from Manichean documents, most of which are otherwise not extant. See especially in his works the book of Faustus the Manichean, with his refutation of it (Op. tom. viii.), and the Epistola Fundamenti of Manes himself, also quoted by St. Augustine in his reply to it. Manes appears to have belonged to the race of the Magi, and to have been skilled in their learning. We find him at the court of Sapor, highly successful in making converts, until jealousy on the part of the Magi seems to have brought about his death (about 278 A. D.).

As the body, together with the irrational soul, is evil and the work of the spirit of darkness, it is plain that the law of a true life requires an extirpation of all appetites. Dropping the fantastic drapery which enwraps the oriental thought and language, as we have done, it is not difficult to recognize popular ideas of our own age. The "signaculum oris" requires an abstinence from flesh and wine, and from the blasphemy which asserts one first cause for all things, and that the animal body is created by God, and that the Son of God was actually incarnate and died. The ** signaculum manuum" requires abstinence from killing animals, and from acts of natural affection, and from labor for wealth. Finally, the "signaculum sinûs” enjoins perfect celibacy. For whoever procreates a body produces a new prison for a soul of light.

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All this, however, belongs to the "elect." Souls thus perfect will return at death to the kingdom of light; but those not purified must pass into other bodies until they shall have expiated their guilt, and been thoroughly cleansed. As for the auditors," they may hope in a future life to pass into the bodies of the elect, and reach perfect bliss the sooner. (See Mosheim, Comment., cent. iii., 22 39-56, who discusses at great length and with copious quotations the fantastic oriental fables through which Manes and his followers presented their ethical principle.)

From this dualism, whether metaphysical or moral, Christian philosophy escaped by the doctrine of creation, together with that of the essentially negative character of evil. The one, absolute, infinite, and eternal Being needed no pre-existent matter (against the Peripatetic dualism of form or intelligence, and matter), from which to produce the multiplicity of finite beings. Yet they are not emanations from Him, but products of His will, wisdom, and love; that is, of Himself, who is known to us as one under those different relations. An existing dualism, therefore, of the finite and the infinite is grounded on the absolute and eternal One. The finite and sensible finds its unity with the other in that it is made after the pattern of the eternal Logos, who is, in eternity, generated by the one eternal principle. (S. Aug., Confess., b. xi.)

The dualism of practical philosophy, also, was denied. There is no evil substance, for God made all things by nature good. Moral evil is a voluntary deprivation of good on the part of a creature possessed of freedom of choice, as darkness is privation of light, cold of heat, blindness of the power of sight. (S. Aug., Confess., b. vii.; De Ordine, i. 6, 7; ii. 4.) Consequently, there is no perfectly evil being. Such would be a mere negation of existence. How or why any creatures voluntarily deprived themselves of part of the good which they had by nature, reason cannot explain; but the result is a higher good for the universe considered as a whole.

The Lord of Light (GOD) and the Lord of Darkness (Hyle) are both eternal, self-existent, unchangeable. But the worlds of light and darkness, it would seem, Medieval ethics, as a part of Christian philosophy, were co-eternal with these principles. (Eternal emana- without extending these principles, reduced them to tions? If so, the dualism extends throughout all ex-more systematic form; ethical dualism, in opposition istences, as in Parseism.) The Lord of Light is to Manichean influences still prevalent, being avoided called GOD, but it is evident that to the Manichees in the same manner. He cannot be infinite, for, on one side at least, He is limited by evil, by darkness. In fact we find this inference to have been accepted by them.

and war.

From both principles proceed emanations; the children of light, dwelling happily in the world of light; the offspring of darkness (demons) in perpetual discord On this earth, and in men, continually goes on the great struggle between light and darkness. For man has a soul, the life of his body, derived from the evil, and a soul of light, which is an emanation from the good.

Man, then, is composed of matter from the world of darkness, in which dwell two souls, one being this evil animal principle; the other rational, immortal. The first man was descended from the Prince of Darkness,

Good and being are in essence one; the difference is relative to us, the good adding to the concept of being the attribute of desirableness (rationem appetibilis: Aquinas, Sum. Theol., I., v. 1). Every entity, as entity, is good (3), and is called evil in being deprived of what it has by nature. A kingdom of darkness, ruled over by an absolutely evil being, is denied; for such would directly conflict with the principle of creation, and involve a concept contradictory to that of the Divine Infinity (I. 49, 3). There is no existing being evil by nature (I. 63, 4); and when Christian ethics speak of a devil, they simply indicate subordination among the ranks of corrupted (spiritual, intellectual) creatures called demons.

A metaphysical principle underlies these prop