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There have been three suppositions about AElfric. (1) He was identified with AElfric (995—1005), archbishop of Canterbury. This view was upheld by John Bale (III. Maj. Bril. Scriptorum 2nd ed., Basel, 1557-1559; vol. i. p. 149, s.v, Alfric); by Humphrey Wanley (Catalogus librorum septentrionalium, &c., Oxford, 1705, forming vol. ii. of George Hickes's Antiquae literaturae septemtrionalis); by Elizabeth Elstob, The English Saxon Homily on the Birthday of St Gregory (1709; new edition, 1839); and by Edward Rowe Mores, AElfrico, Dorobernensi, archiepiscopo, Commentarius (ed. G. J. Thorkelin, 1789), in which the conclusions of earlier writers on AElfric are reviewed. Mores made him abbot of St Augustine's at Dover, and finally archbishop of Canterbury. (2) Sir Henry Spelman, in his Concina . . .(1639, vol. i. p. 583), printed the Canones ad Wulsinum episcopum, and suggested AElfric Putta or Putto, archbishop of York, as the author, adding some note of others bearing the name. The identity of AElfric the grammarian with AElfric archbishop of York was also discussed by Henry Wharton, in Anglia Sacra (1691, vol. i. pp. 125-134), in a dissertation reprinted in J. P. Migne's Patrologia (vol. 139, pp. 1459-70, Paris, 1853). (3) William of Malmesbuty (De gestis pontificum Anglorum, ed. N. E. S. A. Hamilton, Rolls Series, 1870, p. 406) suggested that he was abbot of Malmesbury and bishop of Crediton. The main facts of his career were finally elucidated by Eduard Dietrich in a series of articles contributed to C. W. Niedner's Zeitschrift fur historische Theologie (vols. for 1855 and 1856, Gotha), which have formed the basis of all subsequent writings on the subject.

Sketches of AElfric's career are in B. Ten Brink's Early English Literature (to Wiclif) (trans. H. M. Kennedy, New York, 1883, pp. 105-112), and by J. S. Westlake in The Cambridge History of English Literature (vol. i., 1907, pp. 116-129). An excellent bibliography and account of the critical apparatus is given in Dr R. Wulker's Grundriss zur Geschichte der angelsachsischen Litteratur (Leipzig, 1885; pp. 452-480). See also the account by Professor Skeat in Pt. iv. pp. 8-61 of his edition of the Lives of the Saints, already cited, which gives a full account of the MSS., and a discussion of AElfric's sources, with further bibliographical references; and AElfric, a New Study of his Life and Writings, by Miss C. L. White (Boston, New York and London, 1898) in the "Yale Studies in English.'' Alcuini Interrogationes Sigewulfi Presebyteri in Genesin (ed. G. E. McLean, Halle, 1883) is attributed to AElfric by its editor. There are other isolated sermons and treatises by AElfric, printed in vol. iii. of Grein's Bibl. v. A.S. Prosa.

1 See A Testimonie of Antiquitie, shewing the auncient fayth in the Church of England touching the sacrament of the body and bloude of the Lord here publikely preached, printed by John Day (1567). It was quoted in John Foxe's Actes and Monuments (ed. 1610)) 2 Ed. J. Zupitza in Sammlung englischer Denkmaler (vol. i., Berlin, 1880). 3 Edited by Edward Thwaites as Heptateuchus (Oxford 1698); modern edition in Grein's Bibliothek der A. S. Prosa (vol. i. Cassel and Gottingen, 1872). See also B. Assmann, Abt AElfric's . . . Esther (Halle, 1885), and Abt AElfric's Judith (in Anglia, vol. x.). 4 Printed by Benjamin Thorpe in Ancient Laws and Institutes of England (1840), with the later pastoral for Wulfstan. 5 See E. Breck, A Fragment of AElfric; translation of AEthelwold's De Consuetudine Monachorum and its relation to other MSS. (Leipzig 1887). 6 Ilmington, on the borders of Warwickshire and Gloucestershire. 7 Included by J. Stevenson in the Chron. Monast. de Abingon (vol. ii. pp. 253-266, Rolls Series, 1858). 8 See Oswald Cockayne, Leechdoms, Wortcunning and Starcraft (vol. iii., 1866, pp. xiv.-xix. and pp. 233 et. seq.) in the Rolls Series. 9 See an article by J. Zupitza in the Zeitschrift fur deutsches Altertum (vol. xix., new series, 1887).

AELIA CAPITOLINA, the city built by the emperor Hadrian, A.D. 131, and occupied by a Roman colony, on the site of Jerusalem (q.v.), which was in ruins when he visited his Syrian dominions. Aelia is derived from the emperor's family name, and Capilolina from that of Jupiter Capitolinus, to whom a temple was built on the site of the Jewish temple.

AELIAN (AELIANUS TACTICUS), Greek military writer of the 2nd century A.D., resident at Rome. He is sometimes confused with Claudius Aelianus, the Roman writer referred to below. Aelian's military treatise, Taktike Theoria, is dedicated to Hadrian, though this is probably a mistake for Trajan, and the date A.D. 106 has been assigned to it. It is a handbook of Greek, i.e. Macedonian, drill and tactics as practised by the Hellenistic successors of Alexander the Great. The author claims to have consulted all the best authorities, the chief of which was a lost treatise on the subject by Polybius. Perhaps the chief value of Aelian's work lies in his critical account of preceding works on the art of war, and in the fulness of his technical details in matters of drill. Critics of the 18th century—-Guichard Folard and the prince de Ligne—were unanimous in thinking Aelian greatly inferior to Arrian, but both on his immediate successors, the Byzantines, and on the Arabs, who translated the text for their own use, Aelian exercised a great influence. The emperor Leo VI. incorporated much of Aelian's text in his own work on the military art. The Arabic version of Aelian was made about 1350. In spite of its academic nature, the copious details to be found in the treatise rendered it of the highest value to the army organizers of the 16th century, who were engaged in fashioning a regular military system out of the semi-feudal systems of previous generations. The Macedonian phalanx of Aelian had many points of resemblance to the solid masses of pikemen and the "squadrons'' of cavalry of the Spanish and Dutch systems, and the translations made in the 16th century formed the groundwork of numerous books on drill and tactics. Moreover, his works, with those of Xenophon, Polybius, Aeneas and Arrian, were minutely studied by every soldier of the 16th and 17th centuries who wished to be master of his profession. It has been suggested that Aellan was the real author of most of Arrian's Tactica, and that the Taktike Theoria is a later revision of this original, but the theory is not generally accepted.

The first edition of the Greek text is that of Robortelli (Venice, 1552); the Elzevir text (Leiden, 1613) has notes. The text in W. Rustow and H. Kochly's Gricchische Kriegsschriftsteller (1855) is accompanied by a translation, notes and reproductions of the original illustrations. A Latin translation by Theodore Gaza of Thessalonica was included in the famous collection Veteres de re mililari scriptores (Rome and Venice, 1487, Cologne, 1528, &c.). The French translation of Machault, included in his Milices des Grecs et Romains (Paris, 1615) and entitled De la Sergenterie des Grecs, a German translation from Theodore Gaza (Cologne, 1524), and the English version of Jo. B(ingham), which includes a drill-manual of the English troops in the Dutch service, Tacticks of Aelian (London, 1616) are of importance in the military literature of the period. A later French translation by Bouchard de Bussy. La Milice des Grecs on Tactique d'Elien (Paris 1737 and 1757); Baumgartner's German translation in his incomplete Sammlung aller Kriegsschriftsteller der Griechen (Mannheim and Frankenthal, 1779), reproduced in 1786 as Von Schlachtordnungen, and Viscount Dillon's English version (London, 1814) may also be mentioned. See also R. Forster, Studien zu den griechischen Taktikern (Hermes, xii., 1877, pp. 444-449); F. Wustenfeld, Das Heerwesen der Muhammedaner und die arabische Uebersetzung der Taktik des Aelianus (Gottingen, 1880); M. Jahns, Gesch. der Kriegswissenscharen, i. 95-97 (Munich, 1889); Rustow and Kochly, Gesch. des griechischen Kriegswesens (1852). A. de Lort-Serignan, La Phalange (1880); P. Serre, Etudes sur L'histoire militaire et maritime des Grecs et des Romains (1887); K. K. Muller, in Pauly-Wissowa, Realencyclopadie (Stuttgart, 1894).

AELIAN (CLAUDIUS AELIANUS), Roman author and teacher of rhetoric, born at Praeneste, flourished under Septimius Severus and probably outlived Elagabalus (d. 222). He spoke Greek so perfectly that he was called "honey-tongued'' (meliglossos); Although a Roman he preferred Greek authors, and wrote in Greek himself. His chief works are: On the Nature of Animals, curious and interesting stories of animal life, frequently used to convey moral lessons (ed. Schneider, 1784; Jacobs, 1832); Various History-for the most part preserved only in an abridged form—consisting mainly of anecdotes of men and customs (ed. Lunemann, 1811). Both works are valuable for the numerous excerpts from older writers. Considerable fragments of two other works On Providence and Divine Manifestations are preserved in Suidas; twenty Peasants' Letters, after the manner of Alciphron but inferior, are also attributed to him.

Editio princeps of complete works by Gesner, 1556; Hercher, 1864-1866. English translation of the Various History only by Fleming, 1576, and Stanley, 1665; of the Letters by Quillard (French), 1895.

AELRED, AILRED, ETHELRED (1100-1166), English theologian, historical writer and abbot of Rievaulx, was born at Hexham about the year 1109. In his youth he was at the court of Scotland as an attendant of Henry, son of David I. He was in high favour with that sovereign, but renounced the prospect of a bishopric to enter the Cistercian house of Rievaulx in Yorkshire, which was founded in 1131 by Walter Espec. Here AElred remained for some time as master of the novices, but between the years 1142 and 1146 was elected abbot of Revesby in Lincolnshire and migrated thither. In 1146 he became abbot of Rievaulx. He led a life of the severest asceticism, and was credited with the power of working miracles; owing to his reputation the numbers of Rievaulx were greatly increased. In 1164 he went as a missionary to the Picts of Galloway. He found their religion at a low ebb, the regular clergy apathetic and sensual, the bishop little obeyed, the laity divided by tho family feuds of their rulers, unchaste and ignorant. He induced a Galwegian chief to take the habit of religion, and restored the peace of the country. Two years later he died of a decline, at Rievaulx, in the fifty-seventh year of his age. In the year 1191 he was canonized. His writings are voluminous and have never been completely published. Amongst them are homilies "on the burden of Babylon in Isaiah''; three books "on spiritual friendship''; a life of Edward the Confessor; an account of miracles wrought at Hexham, and the tract called Relatio de Standardo. This last is an account of the Battle of the Standard (1138), better blown than the similar account by Richard of Hexham, but less trustworthy, and in places obscured by a peculiarly turgid rhetoric.

See the Vita Alredi in John of Tynemouth's Nova Legenda Anglie (ed. C. Horstmann, 1901, vol. i. p. 4i), whence it was taken by Capgrave. From Capgrave the work passed into the Bollandist Acta Sanctorum (Jan. ii p. 30). This life is anonymous, but of an early date. The most complete printed collection of AElred's works is in Migne's Patrologia Latina, vol. cxcv.; but this does not include the Miracula Hagulstatdensis Ecclesiae which are printed in J. Raine's Priory of Hexham, vol. i. (Surtees Society, 1864).—A complete list of works attributed to AElred is given in T. Tanner's Bibliotheca Britannico-Hibernica (1748), pp. 247,248. The Relatio de Standardo has been critically edited by R. Howlett in Chronicles, &c., of Stephen, Henry II. and Richard I., vol. iii. (Rolls Series, 1886). . (H. W. C. D.)

AEMILIA VIA, or AEMILIAN WAY. (1) A highroad of Italy, constructed in 187 B.C. by the consul M. Aemilius Lepidus, from whom it taves its name; it ran from Ariminum to Placentia, a distance of 176 m. almost straight N.W., with the plain of the Po (Padus) and its tributaries on the right, and the Apennines on the left. The 79th milestone from Ariminum found in the bed of the Phenus at Bononia records the restoration of the road by Augustus from Ariminum to the river Trebia in 2 B.C. (Notiz. Scav., 1902, 539). The bridge by which it crossed the Sillaro was restored by Trajan in A.D. 100 (Notizie degli Scavi, 1888, 621). The modern highroad follows the ancient line, and some of the original bridges still exist. After Augustus, the road gave its name to the district which formed the eighth region of Italy (previously known as Gallia or Provincia Ariminum), at first in popular usage (as in Martial), but in official language as early as the 2nd century; it is still in use (see EMILIA). The district was bounded on the N. by the Padus, E. by the Adriatic, S. by the river Crustumium (mod. Conca), and W. by the Apennines and the Ira (mod. Staffora) at Iria (mod. Voghera), and corresponds approximately with the modern district.

(2) A road constructed in 109 B.C. by the censor M. Aemillus Scaurus from Vada Volaterrana and Luna to Vada Sabatia and thence over the Apennines to Ilertona (Tortona), where it joined the Via Postumia from Genua to Cremona. We must, however (as Mommsen points out in C.I.L. v. p. 885), suppose that the portion of the coast road from Vada Volaterrana to Genua at least must have existed before the construction of the Via Postumia in 148 B.C. Indeed Polybius (iii. 39. 8) tells us (and this must refer to the time of the Gracchi if not earlier) that the Romans had in his time built the coast road from the Rhone to Carthago Nova; and it is incredible that the coast road in Italy itself should not have been constructed previously. It is, however, a very different thing to open a road for traffic, and so to construct it that it takes its name from that construction in perpetuity. (, As.)

AEMILIUS, PAULUS (PAOLO EMILIO ) (d. 1529), Italian historian, was born at Verona. He obtained such reputation in his own country that he was invited to France in the reign of Charles VIII., in order to write in Latin the history of the kings of France, and was presented to a canonry in Notre Dame. He enjoyed the patronage and support of Louis XII. He died at Paris on the 5th of May 1529. His De Rebus gestis Francorum was translated into French in 1581, and has also been translated into Italian and German.

AENEAS, the famous Trojan hero, son of Anchises and Aphrodite, one of the most important figures in Greek and Roman legendary history. In Homer, he is represented as the chief bulwark of the Trojans next to Hector, and the favourite of the gods, who frequently interpose to save him from danger (Iliad, v. 311). The legend that he remained in the country after the fall of Troy, and founded a new kingdom (Iliad, xx. 308; Hymn to Aphrodite, 196) is now generally considered to be of comparatively late origin. The story of his emigration is post-Homeric, and set forth in its fullest development by Virgil in the Aeneid. Carrying his aged father and household gods on his back and leading his little son Ascanius by the hand, he makes his way to the coast, his wife Creusa being lost during the confusion of the flight. After a perilous voyage to Thrace, Delos, Crete and Sicily (where his father dies), he is cast up by a storm, sent by Juno, on the African coast. Refusing to remain with Dido, queen of Carthage, who in despair puts an end to her life, he sets sail from Africa, and after seven years' wandering lands at the mouth of the Tiber. He is hospitably received by Latinus, king of Latium, is betrothed to his daughter Lavinia, and founds a city called after her, Lavinium. Turnus, king of Rutuli, a rejected suitor, takes up arms against him and Latinus, but is defeated and slain by Aeneas on the river Numicius. The story of the Aeneid ends with the death of Turnus. According to (i. 1. 2), Aeneas, after reigning a few years over Latium, is slain by the Rutuli; after the battle, his body cannot be found, and he is supposed to have been carried up to heaven. He receives divine honours, and is worshipped under the name of Jupiter Indiges (Dionysius Halle. i. 64).

See J. A. Hild, La Legende d'Enee avant Vergile (1883); F. Cauer, De Fabuls Graecis ad Romam conditum pertinentibus (1884) and Die Romische Aeneassage, von Naevius bis Vergilius (1886); G. Boissier, "La Legende d'Enee'' in Revue des Deux Mondes, Sept. 1883; A. Forstemann, Zur Geschichte des Aeneasmythus (1894); articles in Pauly-Wissowa's Realencyclopadie (new ed., 1894); Roscher's Lexicon der Mythologie; Daremberg and Saglio's Dictionnaire des antiquites; Preller's Griechische und romische Mythologie; and especially Schwegler, Romische Geschichte (1867).

Romances.—-The story of Aeneas, as a sequel to the legend of Troy, formed the subject of several epic romances in the middle ages. The Roman d'Eneas (c. 1160, or later), of uncertain authorship (attributed by some to Benoit de Sainte-More), the first French poem directly imitated from the Aeneid, is a fairly close adaptation of the oriinal. The trouvere, however, omits the greater part of the wanderings of Aeneas, and adorns his narrative with gorgeous descriptions, with accounts of the marvellous properties of beasts and stones, and of single combats among the knights who figure in the story. He also elaborates the episodes most attractive to his audience, notably those of Dido and Aeneas and Lavinia, the last of whom plays a far more important part than in the Aeneid. Where possible, he substitutes human for divine intervention, and ignores the idea of the glorification of Rome and Augustus, which dominates the Virgilian epic. On this work were founded the Eneide or Eneit (between 1180 and 1190) of Heinrich von Veldeke, written in Flemish and now only extant in a version in the Thuringian dialect, and the Eneydos, written by William Caxton in 1490. See Eneas, ed. J. Salverdo de Grave (Halle, 1891); see also A. Litteraire de la France, xix.; Veldeke's Encide, ed. Ettmuller (Leipzig, 1852) and O. Behaghel (Heilbronn, 1882); Eneydos, ed. F. J. Furnivall (1890). For Italian versions see E. G. Parodi in Studi di filologia romanza (v. 1887).

AENEAS TACTICUS (4th century B.C.), one of the earliest Greek writers on the art of war. According to Aelianus Tacticus and Polybius, he wrote a number of treatises (Upomnemata) on the subject; the only one extant deals with the best methods of defending a fortified city. An epitome of the whole was made by Cineas, minister of Pyrrhus, king of Epirus. The work is chiefly valuable as containing a large number of historical illustrations. Aeneas was considered by Casaubon to have been a contemporary of Xenophon and identical with the Arcadian general Aeneas of Stymphalus, whom Xenophon (Hellenica, vii. 3) mentions as fighting at the battle of Mantinea (362 B.C.). Editions in I. Casaubon's (1619), Gronovius' (1670) and Ernesti's (1763) editions of Polybius; also.separately, with notes, by J. C. Orelli (Leipzig, 1818). Other texts are those of W. Rustow and H. Kochly (Griechische Kriegsschriftsteller, vol. i. Leipzig, 183S) and A. Hug, Prolegomena Critica ad Aeneae editionem (Zurich University, 1874). See also Count Beausobre, Commentaires sur la defense des places d'Aeneas (Amsterdam, 1757); A. Hug, Aeneas von Stymphalos (Zurich, 1877); C. C. Lange, De Aeneae commentario poliorcetico (Berlin, 1879); M. H. Meyer, Observationes in Aeneam Tacticum (Halle, 1835) ; Haase, in Jahns Jahrbuch, 1835, xiv. 1 ; Max Jahns, Gesch. der Kriegswissenschaften, i. pp. 26-28 (Munich, 1889) ; Ad. Bauer, in Zeitschrift fur allg. Geschichte, &c., 1886, i.; T. H. Williams in American Journal of Philology, xxv. 4; E. Schwartz in Pauly-Wissowa, Realencyclopadie (Stuttgart, 1894).

AENESIDEMUS, Greek philosopher, was born at Cnossus in Crete and taught at Alexandria, probably during the first century B.C. He was the leader of what is sometimes known as the third sceptical school and revived to a great extent the doctrine of Pyrrho and Timon. His chief work was the Pyrrhonian Principles addressed to Lucius Tubero. His philosophy consisted of four main parts, the reasons for scepticism and doubt, the attack on causality and truth, a physical theory and a theory of morality. Of these the two former are important. The reasons for doubt are given in the form of the ten "tropes'': (1) different animals manifest different modes of perception; (2) similar differences are seen among individual men; (3) even for the same man, sense-given data are self-contradictory, (4) vary from time to time with physical changes, and (5) accord- ing to local relations; (6) and (7) objects are known only in- directly through the medium of air, moisture, &c., and are in a condition of perpetual change in colour, temperature, size and motion; (8) all perceptions are relative and interact one upon another; (9) Our impressions become less deep by repetition and custom; and (10) all men are brought up with different beliefs, under different laws and social conditions. Truth varies infinitely under circumstances whose relative weight cannot be accurately gauged. There is, therefore, no absolute knowledge, for every man has different perceptions, and, further, arranges and groups his data in methods peculiar to himself; so that the sum total is a quantity with a purely subjective validity. The second part of his work consists in the attack upon the theory of causality, in which he adduces almost entirely those considerations which are the basis of modern scepticism. Cause has no existence apart from the mind which perceives; its validity is ideal, or, as Kant would have said, subjective. The relation between cause and effect is unthinkable. If the two things are different, they are either simultaneous or in succession. If simultaneous, cause is effect and effect cause. If not, since effect cannot precede cause, cause must precede effect, and there must be an instant when cause is not effective, that is, is not itself. By these and similar arguments he arrives at the fundamental principle of Scepticism, the radical and universal opposition tion of causes; panti logo logos antikeitai. Having reached this conclusion, he was able to assimilate the physical theory of Heraclitus, as is explained in the Hypotyposes of Sextus Empiricus. For admitting that contraries co-exist for the perceiving subject, he was able to assert the co-existence of contrary qualities in the same object. Having thus disposed of the ideas of truth and causality, he proceeds to undermine the ethical criterion, and denies that any man can aim at Good, Pleasure or Happiness as an absolute, concrete ideal. All actions are product of pleasure and pain, good and evil. The end of ethical endeavour is the conclusion that all endeavour is vain and illogical. The main tendency of this destructive scepticism is essentially the same from its first crystallization by Aenesidemus down to the most advanced sceptics of to-day (ree SCEPTICISM). For the immediate successors of Aenesidemus see AGRIPPA, SEXTUS EMPIRICUS. See also CARNEADES and ARCESILAUS. Of the Porroneioi logoi nothing remains; we have, however, an analysis in the Myriobiblion of Photius. See Zeller's History of Greek Philosophy; F. Saisset, AEnesideme, Pascal, Kant; Ritter and Preller, sec. sec. 364-87O.

AEOLIAN HARP (Fr. harpe eolienne; Ger. Aolsharfe, Windharfe; Ital. arpa d'Eolo), a stringed musical instrument, whose name is derived from Aeolus, god of the wind. The aeolian harp consists of a sound-box about 3 ft long, 5 in. wide, and 3 in. deep, made of thin deal, or preferably of pine, and having beech ends to hold the tuning-pins and hitch-pins. A dozen or less catgut strings of different thickness, but tuned in exact unison, and left rather slack, are attached to the pins, and stretched over two narrow bridges of hard wood, one at each end of the sound-board, which is generally provided with two rose sound-holes. To ensure a proper passage for the wind, another pine board is placed over the strings, resting on pegs at the ends of the sound-board, or on a continuation of the ends raised from 1 to 3 in. above the strings. Kaufmann of Dresden and Heinrich Christoph Koch, who improved the aeolian harp, introduced this contrivance, which was called by them Windfang and Windflugel; the upper board was prolonged beyond the sound-box in the shape of a funnel, in order to direct the current of air on to the strings. The aeolian harp is placed across a window so that the wind blows obliquely across the strings, causing them to vibrate in aliquot parts, i.e. (the fundamental note not being heard) the half or octave, the third or interval of the twelfth, the second Octave, and the third above it, in fact the upper partials of the strings in regular succession. With the increased pressure of the wind, the dissonances of the 11th and 13th overtones are heard in shrill discords, only to give place to beautiful harmonies as the force of the wind abates. The principle of the natural vibration of strings by the pressure of the wind was recognized in ancient times; King David, we hear from the Rabbinic records, used to hang his kinnor (kithara) over his bed at night, when it sounded in the midnight breeze. The same is related of St Dunstan of Canterbury, who was in consequence charged with sorcery. The Chinese at the present day fly kites of various sizes, having strings stretched across apertures in the paper, which produces the effect of an aerial chorus.

See Athanasius Kircher, Musurgia Universalis, where the aeolian harp is first described (1602-1608), p. 148; Mathew Young, Bishop of Clonfert, Enquiry into the Principal Phenomena of Sounds and Musical Strings pp. 170-182 (London, 1784); Gottingen Pocket Calendar (1792); Mendel's Musikalisches Conversations-Lexikon, article "Aeolsharfe.', An illustration is given in Rees' Encyclopedia, plates, vol. ii. Misc. pl. xxv (K. S.)

AEOLIS (AEOLIA), an ancient district of Asia Minor, colonized at a very early date by Aeolian Greeks. The name was applied to the coast from the river Hermus to the promontory of Lecture, i.o. between Ionia to S. and Troas to N. The Aeolians founded twelve cities on the mainland, including Cyme, and numerous towns in Mytilene: they were said also to have settled in the Troad and even within the Hellespont.

AEOLUS, in Greek mythology, according to Homer the son of Hippotes, god and father of the winds, and ruler of the island of Aeolia. In the Odyssey (x. I) he entertains Odysseus, gives him a favourable wind to help him on his journey, and a bag in which the unfavourable winds have been confined. Out of curiosity. or with the idea that it contains valuable treasures, Odysseus' companions open the bag; the winds escape and drive them back to the island, whence Aeolus dismisses them with bitter reproaches. According to Virgil, Aeolus dwells on one of the Aeolian islands to the north of Sicily, Lipara or Strongyle (Stromboll), where he keeps the winds imprisoned in a vast cavern (Virgil, Aen. i. 52). Another genealogy makes him the son of Poseidon and Arne, granddaughter of Hippotes, and a descendant of Aeolus, king of Magnesia in Thessaly, the mythical ancestor of the tribe of the Aeolians (Diodorus iv. 67).

AEON, a term often used in Greek (aion) to denote an indefinite or infinite duration of time; and hence, by metonymy, a being that exists for ever. In the latter sense it was chiefly used by the Gnostic sects to denote those eternal beings or manifestations which emanated from the one incomprehensible and ineffable God. (See GNOSTICISM.)

AEPINUS, FRANZ ULRICH THEODOR (1724-1802), German natural philosopher, was born at Rostock in Saxony on the 13th of December 1724. He was descended from John Aepinus (1499-1553), the first to adopt the Greek form (aipernos) of the family name Hugk or Huck, and a leading theologian and controversialist at the time of the Reformation. After studying medicine for a time, Franz Aepinus devoted himself to the physical and mathematical sciences, in which he soon gained such distinction that he was admitted a member of the Berlin academy of sciences. In 1757 he settled in St Petersburg as member of the imperial academy of sciences and professor of physics, and remained there till his retirement in 1798. The rest of his life was spent at Dorpat, where he died on the 10th of August 1802. He enjoyed the special favour of the empress Catherine II., who appointed him tutor to her son Paul, and endeavoured, without success, to establish normal schools throughout the empire under his direction. Aepinus is best known by his researches, theoretical and experimental, in electricity and magnetism, and his principal work, Tentamen Theoriae Electricitatis et Magnetismi, published at St Petersburg in 1759, was the first systematic and successful attempt to apply mathematical reasoning to these subjects. He also published a treatise, in 176I, De distributione caloris per tellurem, and he was the author of memoirs on different subjects in astronomy, mechanics, optics and pure mathematics, contained in the journals of the learned societies of St Petersburg and Berlin. His discussion of the effects of parallax in the transit of a planet over the sun's disc excited great interest, having appeared (in 1764) between the dates of the two transits of Venus that took place in the 18th century.

AEQUI, an ancient people of Italy, whose name occurs constantly in Livy,s first decade as hostile to Rome in the first three Centuries of the city's existence. They occupied the upper reaches of the valleys of the Anio, Tolenus and Himella; the last two being mountain streams runing northward to join the Nar. Their chief centre is said to have been taken by the Romans about 484 B.C. (Diodorus xi. 40) and again about ninety years later (id. xiv. 106), but they were not finally subdued Until the end of the second Samnite war (Livy ix. 45,; x. 1; Diod. xx. 101), when they seem to have received a limited form of franchise (Cic. Off. i. II, 35). All we know of their subsequent political condition is that after the Social war the folk of Cliternia and Nersae appear united in a res Publica Aequiculorum, which was a municipium of the ordinary type (C.I.L. ix. p. 388). The Latin colonies of Alba Fucens (304 B.C.) and Carsioll (298 B.C.) must have spread the use of Latin (or what passed as such) all over the district; through it by the chief (and for some time the only) route (Pia Valeria) to Luceria and the south. Of the language spoken by the Aequi before the Roman conquest we have no record; but since the Marsi (q.v.), who lived farther east, spoke in the 3rd century B.C. a dialect closely akin to Latin, and since the Hernici (q.v.), their neighbours to the south-west, did the same, we have no ground for separating any of these tribes from the Latian group (see LATINI). If we could be certain of the origin of the a in their name and of the relation between its shorter and its longer form (note that the i in Aequicidus is long—Virgil, Aen. vii. 74——which seems to connect it with the locative of aequum "a plain,'' so that it would mean "dwellers in the plain''; but in the historical period they certainly lived mainly in the hills), we should know whether they were to be grouped with the q or the p dialects, that is to say, with Latin on the one hand, which preserved an original q, or with the dialect of Velitrae, commonly called Volscian (and the Volsci were the constant allies of the Aequi), on the other hand, in which, as in the Iguvine and Samnite dialects, an original q is changed into p. There is no decisive evidence to show whether the q in Latin aequus represents an Indo-European q as in Latin quis, Umbro-Volsc. pis, or an Indo-European k+u as in equus, Umb. ekvo-. The derivative adjective Aequicus might be taken to range them with the Volsci rather than the Sabini, but it is not clear that this adjective was ever used as a real ethnicon; the name of the tribe is always Aeqai, or Aequicoli. At the end of the Republican period the Aequi appear, under the name Aequiculi or Aequicoh, organized as a municipium, the territory of which seems to have comprised the upper part of the valley of the Salto, still known as Cicolano. It is probable, however, that they continued to live in their villages as before. Of these Nersae (mod. Nesce) was the most considerable. The polygonal terrace walls, which exist in considerable numbers in the district, are shortly described in Romische Mitteilungen (1903), 147 seq., but require further study. See further the articles MARSI, VOLSCI, LATINI, and the references there given; the place-names and other scanty records of the dialect are collected by R. S. Conway. The Italic Dialects, pp. 300 ff. (R. S. C.)

AERARII (from Lat. aes, in its subsidiary sense of "polltax''), originally a class of Roman citizens not included in the thirty tribes of Servius Tullius, and subject to a poll-tax arbitrarily fixed by the censor. They were (1) the inhabitants of conquered towns which had been deprived of local self-government, who possessed the jus eonubii and ius commercii, but no political rights; Caere is said to have been the first example of this (353 B.C.); hence the expression "in tabulas Caeritum referre'' came to mean "to degrade to the status of an aerarius'': (2) full citizens subjected to civil degradation (infamia) as the result of following certain professions (e.g. acting), of dishonourable acts in private life (e.g. bigamy) or of conviction for certain crimes; (3) persons branded by the censor. Those who were thus excluded from the tribes and centuries had no vote, were incapable of filling Roman magistracies and could not serve in the army. According to Mommsen, the aerarii were originally the non-assidui (non-holders of land), excluded from the tribes, the comitia and the army. By a reform of the censor Appius Claudius in 312 B.C. these non-assidui were admitted into the tribes, and the aerarii as such disappeared. But in 304, Fabius Rullianus limited them to the four city tribes, and from that time the term meant a man degraded from a higher (country) to a lower (city) tribe, but not deprived of the right of voting or of serving in the army. The expressions "tribu movere'' and "aerarium facere,': regarded by Mommsen as identical in meaning ("to degrade from a higher tribe to a lower,'), are explained by A. H. J. Greenidge—-the first as relegation from a higher to a lower tribe or total exclusion from the tribes, the second as exclusion from the centuries. Other views of the original aerarii are that they were—artisans and freedmen (Niebuhr); inhabitants of towns united with Rome by a hospitium publicum, who had become domiciled on Roman territory (Lange); only a class of degraded citizens, including neither the cives sine suffragio nor the artisans (Madvig); identical with the capite censi of the Servian constitution (Belot, Greenidge). See A. H. J. Greenidge, Infamia in Roman Law (1894), where Mommsen's theory is criticized; E. Belot, Histoire des chevaliers romains, i. p. 200 (Paris, 1866); L. Pardon, De Aerariis (Berlin, 1853); P. Willems, Le Droit public romain (1883); A. S. Wilkins in Smith's Dict. of Greek and Roman Antiquities (3rd ed., 189I); and the usual handbooks of antiquities.

AERARIUM (from Lat. aes, in its derived sense of "money'') the name (in full, aerarium stabulum, treasure-house) given in ancient Rome to the public treasury, and in a secondary sense to the public finances. The treasury contained the moneys and accounts of the state, and also the standards of the legions; the public laws engraved on brass, the decrees of the senate and other papers and registers of importance. These public treasures were deposited in the temple of Saturn, on the eastern slope of the Capitoline hill, and, during the republic, were in charge of the urban quaeators (see QUAESTOR), under the superintendence and control of the senate. This arrangement continued (except for the year 45 B.C., when no quaestors were chosen) until 28 B.C., when Augustus transferred the aerarium to two praojecti aerarii, chosen annually by the senate from ex-praetors; in 23 these were replaced by two praetors (praetores aerarii or ad aerarium), selected by lot during their term of office; Claudius in A.D. 44 restored the quaestors, but nominated by the emperor for three years, for whom Nero in 56 substituted two ex-praetors, under the same conditions. In addition to the common treasury, supported by the general taxes and charged with the ordinary expenditure, there was a special reserve fund, also in the temple of Saturn, the aerarium sanctum (or sanctius), probably originally consisting of the spoils of war, afterwards maintained chiefly by a 5% tax on the value of all manumitted slaves, this source of revenue being established by a lex Manlia in 357. This fund was not to be touched except in cases of extreme necessity (Livy vii. 16, xxvii. 10). Under the emperors the senate continued to have at least the nominal management of the aerarium, while the emperor had a separate exchequer, called fiseus. But after a time, as the power of the emperors increased and their jurisdiction extended till the senate existed only in form and name, this distinction virtually ceased. Besides creating the fiscus, Augustus also established in A.D. 6 a military treasury (aerarium militare), containing all moneys raised for and appropriated to the maintenance of the army, including a pension fund for disabled soldiers. It.was largely endowed by the emperor himself (see Monumentum Ancyranum, iii. 35) and supported by the proceeds of the tax on public sales and the succession duty. Its administration was in the hands of three praefecti aerarii militaris, at first appointed by lot, but afterwards by the emperor, from senators of praetorian rank, for three years. The later emperors had a separate aerarium privatum, containing the moneys allotted for their own use, distinct from the fiscus, which they administered in the interests of the empire.

The tribuni aerarii have been the subject of much discussion. They are supposed by some to be identical with the curatores tribuum, and to have been the officials who, under the Servian organization, levied the war-tax (tributum) in the tribes and the poil-tax on the aerarii (q.v.). They also acted as paymasters of the equites and of the soldiers on service in each tribe. By the lex Aurella (70 B.C.) the list of judices was composed, in addition to senators and equites, of tribuni aerarii. Whether these were the successors of the above, or a new order closely connected with the equites, or even the same as the latter, is uncertain. According to Mommsen, they were persons who possessed the equestrian census, but no public horse. They were removed from the list of judices by Caesar, but replaced by Augustus. According to Madvig, the original tribuni aerarii were not officials at all, but private individuals of considerable means, quite distinct from the curatores tribuuin, who undertook certain financial work connected with their own tribes. Then, as in the case of the equites, the term was subsequently extended to include all those who possessed the property qualification that would have entitled them to serve as tribuni aerarii. See Tacitus, Annals, xiii. 29, with Furneaux's notes; O. Hirschfeld, "Das Aerarium militare in der romischen Kaiserzeit,'' in Fleckeisen's Jahrbuch, vol. xcvii. (1868); S. Herrlich, De Aerario et Fisco Romanorum (Berlin, 1872); and the usual handbooks and dictionaries of antiquities. On the tribuni aerarii see E. Belot, Hist. des chevaliers romains, ii. p. 276; J. N. Madvig, Opuscula Academica, ii. p. 242; J. B. Mispoulet, Les Institutions politiques des Romains (1883), ii. p. 208; Mommsen, Romisches Staatsrecht, iii. p. 189; A. S. Wilkins in Smith's Dictionary of Greek and Roman Antiquities (3rd ed., 1890).

AERATED WATERS. Waters charged with a larger proportion of carbon dioxide than they will dissolve at ordinary atmospheric pressure occur in springs in various parts of the world (see MINERAL WATERS). Such waters, which also generally hold in solution a considerable percentage of saline constituents, early acquired a reputation as medicinal agents, and when carbon dioxide ("fixed air'') became familiar to chemists the possibility was recognized, as by Joseph Priestley (Directions for impregnating water with fixed air . . . to communicate the peculiar Spirit and Virtues of Pyrmont water, 1772), of imitating them artificially. Many of the ordinary aerated waters of commerce, however, do not pretend to reproduce any known natural water; they are merely beverages owing their popularity to their effervescing properties and the flavour imparted by a small quantity of some salt such as sodium bicarbonate or a little fruit syrup. Their manufacture on a considerable scale was begun at Geneva so far back as 1790 by Nicholas Paul, and the excellence of the soda water prepared in London by J. Schweppe, who had been a partner of Paul's, is referred to by Tiberius Cavallo in his Essay on the Medicinal Properties of Factitious Airs, published in 1798. Many forms of apparatus are employed for charging the water with the gas. A simple machine for domestic use, called a gasogene or seltzogene, consists of two strong glass globes connected one above the other by a wide glass tube which rises nearly to the top of the upper and smaller globe. Surmounting the small globe there is a spring valve, fitted to a narrow tube that passes through the wide tube to the bottom of the large globe. To use the machine, the lower vessel is filled with water, and in the upper one, round the base of the wide tube, is placed a mixture, commonly of sodium bicarbonate and tartaric acid, which with water yields carbon dioxide. The valve head is then fastened on, and by tilting the apparatus some water is made to flow through the wide tube from the lower to the upper vessel. The water in the lower globe takes up the gas thus produced, and when required for use is withdrawn by the valve, being forced up the narrow tube by the pressure of the gas. In another arrangement the gas is supplied compressed in little steel capsules, and is liberated into a bottle containing the water which has to be aerated. On a large scale, use is made of continuously acting machinery which is essentially of the type devised by Joseph Bramah. The gas is prepared in a separate generator by the action of sulphuric acid on sodium bicarbonate or whiting, and after being washed is collected in a gas-holder, whence it is forced with water under pressure into a receiver or saturator in which an agitator is kept moving. Some manufacturers buy their gas compressed in steel cylinders. The water thus aerated or carbonated passes from the receiver, in which the pressure may be 100-200 lb. on the square inch, to bottling machines which fill and close the bottles; if beverages like lemonade are being made the requisite quantity of fruit syrup is also injected into the bottles, though sometimes the fruit syrup mixture is aerated in bulk. For soda water sodium bicarbonate should be added to the water before aeration, in varying proportions up to about 15 grains per pint, but the simple carbonated water often does duty instead. Potash water, lithia water and many others are similarly prepared, the various salts being used in such amounts as are dictated by the experience and taste of the manufacturer. Aerated waters are sent out from the factories either in siphons (q.v.) or in bottles; the latter may be closed by corks, or by screw-stoppers or by internal stoppers consisting of a valve, such as a glass ball, held up against an indiarubber ring in the neck by the pressure of the gas. For use in "soda-fountains'' the waters are sent out in large cylinders.

See W. Kirkby, Evolution of artificial Mineral Waters (Manchester, 1902).

AERONAUTICS, the art of "navigating'' the "air.'' It is divisible into two main branches—aerostation, dealing properly with machines which like balloons are lighter than the air, and aviation, dealing with the problem of artificial flight by means of flying machines which, like birds, are heavier than the air, and also with attempts to fly made by human beings by the aid of artificial wings fitted to their limbs.

Historically, aviation is the older of the two, and in the legends of gods or myths of men or animals which are supposed to have travelled through the air, such as Pegasus, Medea's dragons and Daedalus, as well as in Egyptian bas-reliefs, wings appear as the means by which aerial locomotion is effected. In later times there are many stories of men who have attempted to fly in the same way. John Wilkins (1614-1672), one of the founders of the Royal Society and bishop of Chester, who in 1640 discussed the possibility of reaching the moon by volitation, says in his Mathematical Magick (1648) that it was related that "a certain English monk called Elmerus, about the Confessor's time,'' flew from a town in Spain for a distance of more than a furlong; and that other persons had flown from St Mark's, Venice, and at Nuremberg. Giovanni Battista Dante, of Perugia, is said to have flown several times across Lake Trasimene. At the beginning of the 16th century an Italian alchemist who was collated to the abbacy of Tungland, in Galloway, Scotland, by James IV., undertook to fly from the walls of Stirling Castle through the air to France. He actually attempted the feat, but soon came to the ground and broke his thigh-bone in the fall—an accident which he explained by asserting that the wings he employed contained some fowls' feathers, which had an "affinity'' for the dung-hill, whereas if they had been composed solely of eagles' feathers they would have been attracted to the air. This anecdote furnished Dunbar, the Scottish poet, with the subject of one of his rude satires. Leonardo da Vinci about the same time approached the problem in a more scientific spirit, and his notebooks contain several sketches of wings to be fitted to the arms and legs. In the following century a lecture on flying delivered in 1617 by Fleyder, rector of the grammar school at Tubingen, and published eleven years later, incited a poor monk to attempt to put the theory into practice, but his machinery broke down and he was killed.

In Francis Bacon's Natural History there are two passages which refer to flying, though they scarcely bear out the assertion made by some writers that he first published the true principles of aeronautics.

The first is styled Experiment Solitary, touching Flying in the Air —"Certainly many birds of good wing (as kites and the like) would bear up a good weight as they fly; and spreading leathers thin and close, and in great breadth, will likewise bear up a great weight, being even laid, without tilting up on the sides. The further extension of this experiment might be thought upon.'' The second passage is more diffuse, but less intelligible; it is styled Experiment Solitary, touching unequal weight (as of wool and lead or bone and lead); if you throw it from you with the light end forward, it will turn, and the weightier end will recover to be forwards, unless the body be over long. The cause is, for that the more dense body hath a more violent pressure of the parts from the first impulsion, which is the cause (though heretofore not found out, as hath been often said) of all violent motions; and when the hinder part moveth swifter (for that it less endureth pressure of parts) that the forward part can make way for it, it must needs be that the body turn over; for (turned) it can more easily draw forward the lighter part.'' The fact here alluded to is the resistance that bodies experience in moving through the air, which, depending on the quantity of surface merely. must exert a proportionally greater effect on rare substances. The passage itself, however, after making every allowance for the period in which it was written, must be deemed confused, obscure and unphilosophical. In his posthumous work, De Motu Animalium, published at Rome in 1680-1681, G.A.Borelli gave calculations of the enormous strength of the pectoral muscles in birds; and his proposition cciv. (vol. i. pp. 322-326), entitled Est impossibile ut homines pro priis viribus artificiose volare possint, points out the impossibility of man being able by his muscular strength to give motion to wings of sufficient extent to keep him suspended in the air. But during his lifetime two Frenchmen, Allard in 1660 and Besnier about 1678, are said to have succeeded in making short flights. An account of some of the modern attempts to construct flying machines will be found in the article FLIGHT AND FLYING; here we append a brief consideration of the mechanical aspects of the problem.

The very first essential for success is safety, which will probably only be attained with automatic stability. The underlying principle is that the centre of gravity shall at all times be on the same vertical line as the centre of pressure. The latter varies with the angle of incidence. For square planes it moves approximately as expressed by Joessel's formula, C + (0.2 + 0.3 sin a) L, in which C is the distance from the front edge, L the length fore and aft, and a the angle of incidence. The movement is different on concave surfaces. The term aeroplane is understood to apply to flat sustaining surfaces, but experiment indicates that arched surfaces are more efficient. S. P. Langley proposed the word aerodrome, which seems the preferable term for apparatus with wing-line surfaces. This is the type to which results point as the proper one for further experiments. With this it seems probable that, with well-designed apparatus, 40 to 50 lb. can be sustained per indicated h.p., or about twice that quantity per resistance or "thrust'' h.p., and that some 30 or 40 k of the weight can be devoted to the machinery, thus requiring motors, with their propellers, shafting, supplies, &c., weighing less than 20 lb. per h.p. It is evident that the apparatus must be designed to be as light as possible, and also to reduce to a minimum all resistances to propulsion. This being kept in view, the strength and consequent section required for each member may be calculated by the methods employed in proportioning bridges, with the difference that the support (from air pressure) will be considered as uniformly distributed, and the load as concentrated at one or more points. Smaller factors of safety may also have to be used. Knowing the sections required and unit weights of the materials to be employed, the weight of each part can be computed. If a model has been made to absolutely exact scale, the weight of the full-sized apparatus may approximately be ascertained by the formula

$$W' = Wsqrt{left({S'over S} ight)}^3,$$

in which W is the weight of the model, S its surface, and W' and S' the weight and surface of the intended apparatus. Thus if the model has been made one-quarter size in its homologous dimensions, the supporting surfaces will be sixteen times, and the total weight sixty-four times those of the model. The weight and the surface being determined, the three most important things to know are the angle of incidence, the "lift,'' and the required speed. The fundamental formula for rectangular air pressure is well known: P=KV2S, in which P is the rectangular normal pressure, in pounds or kilograms, K a coefficient (0.0049 for British, and 0.11 for metric measures), V the velocity in miles per hour or in metres per second, and S the surface in square feet or in square metres. The normal on oblique surfaces, at various angles of incidence, is given by the formula P = KV2Se, which latter factor is given both for planes and for arched surfaces in the subjoined table:—.


PLANES (DUCHEMIN FORMULA, VERIFIED BY LANGLEY). WINGS (LILIENTHAL). N = P(2sina/(1+sin2a)). Concavity 1 in 12 Angle. Normal. Lift. Drift. Normal. Lift. Drift. Tangential a e ecosa esina e ecosa esina force a -9 deg. 0.0 0.0 0.0 +0.070 -8 deg. 0.040 0.0396 -0.0055 +0.067 -7 deg. 0.080 0.0741 -0.0097 +0.064 -6 deg. 0.120 0.1193 -0.0125 +0.060 -5 deg. 0.160 0.1594 -0.0139 +0.055 -4 deg. 0.200 0.1995 -0.0139 +0.049 -3 deg. 0.242 0.2416 -0.0126 +0.043 -2 deg. 0.286 0.2858 -0.0100 +0.037 -1 deg. 0.332 0.3318 -0.0058 +0.031 0 deg. 0.0 0.0 0.0 0.381 0.3810 -0.0 +0.024 +1 deg. 0.035 0.035 0.000611 0.434 0.434 +0.0075 +0.016 +2 deg. 0.070 0.070 0.00244 0.489 0.489 +0.0170 +0.008 +3 deg. 0.104 0.104 0.00543 0.546 0.545 +0.0285 0.0 +4 deg. 0.139 0.139 0.0097 0.600 0.597 +0.0418 -0.007 +5 deg. 0.174 0.173 0.0152 0.650 0.647 +0.0566 -0.014 +6 deg. 0.207 0.206 0.0217 0.696 0.692 +0.0727 -0.021 +7 deg. 0.240 0.238 0.0293 0.737 0.731 +0.0898 -0.028 +8 deg. 0.273 0.270 0.0381 0.771 0.763 +0.1072 -0.035 +9 deg. 0.305 0.300 0.0477 0.800 0.790 +0.1251 -0.042 10 deg. 0.337 0.332 0.0585 0.825 0.812 +0.1432 -0.050 11 deg. 0.369 0.362 0.0702 0.846 0.830 +0.1614 -0.058 12 deg. 0.398 0.390 0.0828 0.864 0.845 +0.1803 -0.064 13 deg. 0.431 0.419 0.0971 0.879 0.856 +0.1976 -0.070 14 deg. 0.457 0.443 0.1155 0.891 0.864 +0.2156 -0.074 15 deg. 0.486 0.468 0.1240 0.901 0.870 +0.2332 -0.076

The sustaining power, or "lift'' which in horizontal flight must be equal to the weight, can be calculated by the formula L=KV2Secosa, or the factor may be taken direct from the table, in which the "lift'' and the "drift'' have been obtained by multiplying the normal e by the cosine and sine of the angle. The last column shows the tangential pressure on concave surfaces which O. Lilienthal found to possess a propelling component between 3 deg. and 32 deg. and therefore to be negative to the relative wind. Former modes of computation indicated angles of 10 to 15 as necessary for support with planes. These mere prohibitory in consequence of the great "drift''; but the present data indicate that, with concave surfaces, angles of 2 deg. to 5 will produce adequate "lift.'' To compute the latter the angle at which the wings are to be set must first be assumed, and that of @ will generally be found preferable. Then the required velocity is next to be computed by the formula

$$V = sqrt{Lover KSetacosalpha};$$

or for concave wings at +3 deg. :

$$V = sqrt{Wover 0.545KS}.$$

Having thus determined the weight, the surface, the angle of incidence and the required seed for horizontal support, the next step is to calculate the power required. This is best accomplished by first obtaining the total resistances, which consist of the "drift'' and of the head resistances due to the hull and framing. The latter are arrived at preferably by making a tabular statement showing all the spars and parts offering head resistance, and applying to each, the coefficient appropriate to its "master section,'' as ascertained by experiment. Thus is obtained an "equivalent area'' of resistance, which is to be multiplied by the wind pressure due to the speed. Care must be taken to resolve all the resistances at their proper angle of application, and to subtract or add the tangential force, which consists in the surface S, multiplied by the wind pressure, and by the factor in the table, which is, however, 0 for 3 and 32, but positive or negative at other angles. When the aggregate resistances are known, the "thrust h.p.'' required is obtained by multiplying the resistance by the speed, and then allowing for mechanical losses in the motor and propeller, which losses will generally be 50% of indicated h.p. Close approximations are obtained by the above method when applied to full sized apparatus. The following example will make the process clearer. The weight to he carried by an apparatus was 189 lb. on concave wings of 143.5 sq. ft. area, set at a positive angle of 3 deg. There were in addition rear wings of 29.5 sq. ft., set at a negative angle of 3 deg. ; hence, L= 189=.o.oo5XV2X143.5X0.545. Whence

$$V = sqrt{189over 0.005 imes 143.5 imes 0.545 = 22hbox{ miles per hour},$$

at which the air pressure would be 2.42 lb. per sq. ft. The area of spars and man was 17.86 sq. ft., reduced by various coefficients to an "equivalent surface'' of 11.70 sq. ft., so that the resistances were:— Drift front wings, 143.5X0.0285X2.42 . . . .= 9.90 lb. Drift rear wings, 29.5X(o.o43-0.242X0.05235)X2.42 = 2.17 lb. Tangential force at 3 deg. . . . . . . . . = 0.00 lb. Head resistance, 11.70X2.43 . . . . . = 28.31

Total resistance . . . . . . . .= 40.38

Speed 22 miles per hour. Power = (40.38X22)/375 = 2.36 h.p. for the "thrust'' or 4.72 h.p. for the motor. The weight being 189 lb., and the resistance 40.38 lb., the gliding angle of descent was 40.38/189 = tangent of 12 deg. , which was verified by many experiments.

The following expressions will be found useful in computing such projects, with the aid of the table above given:

1. Wind force, F = KV2. 8. Drift, D = KSV2esina 2. Pressure, P = KV2S. 9. Head area E, get an equivalent 3. Velocity, V = sqrt. (W/(KSecosa)) 10. Head resistance, H = EF. 4. Surface S varies as 1/V2. 11. Tangential force, T = Pa 5. Normal, N = KSV2e. 12. Resistance, R = D + H (+ or -) T. 6. Lift, L = KSV2ecsoa. 13. Ft. lb., M = RV. 7. Weight, W = L = Ncosa. 14. Thrust, h.p., = RV/factor.

AEROSTATION.—-Possibly the flying dove of Archytas of Tarentum is the earliest suggestion of true aerostation. According to Aulus Genius (Noctes Atticae) it was a "model of a dove or pigeon formed in wood and so contrived as by a certain mechanical art and power to fly: so nicely was it balanced by weights and put in motion by hidden and enclosed air.'' This "hidden and enclosed air'' may conceivably represent an anticipation of the hot-air balloon, but it is at least as probable that the apparent flight of the dove was a mere mechanical trick depending on the use of fine wires or strings invisible to the spectators. In the middle ages vague ideas appear of some ethereal substance so light that vessels containing it would remain suspended in the air. Roger Bacon (1214-1294) conceived of a large hollow globe made of very thin metal and filled with ethereal air or liquid fire, which would float on the atmosphere like a ship on water. Albert of Saxony, who was bishop of Halberstadt from 1366 to 1390, had a similar notion, and considered that a small portion of the principle of fire enclosed in a light sphere would raise it and keep it suspended. The same speculation was advanced by Francis Mendoza, a Portuguese Jesuit, who died in 1626 at the age of forty-six, and by Gaspar Schott (1608-1666), also a Jesuit and professor of mathematics at Wurzburg, though for fire he substituted the thin ethereal fluid which he believed to float above the atmosphere. So late as 1755 Joseph Galien (1699-1782), a Dominican friar and professor of philosophy and theology in the papal university of Avignon, proposed to collect the diffuse air of the upper regions and to enclose it in a huge vessel extending more than a mile every way, and intended to carry fifty-four times as much weight as did Noah's ark. A somewhat different but equally fantastic method of making heavy bodies rise is quoted by Schott from Lauretus Laurus, according to whom swans' eggs or leather balls filled with nitre, sulphur or mercury ascend when exposed to the sun. Laurus also stated that hens' eggs filled with dew will ascend in the same circumstances, because dew is shed by the stars and drawn up again to heaven by the sun's heat during the day. The same notion is utilized by Cyrano de Bergerac (1619-1655) in his romances describing journeys to the moon and sun, for his French traveller fastens round his body a multitude of very thin flasks filled with the morning's dew, whereby through the attractive power of the sun's heat on the dew he is raised to the middle regions of the atmosphere, to sink again, however, on the breaking of some of the flasks.

A distinct advance on Schott is marked by the scheme for aerial navigation proposed by the Jesuit, Francis Lana (1631-1687), in his book, published at Brescia in 1670, Prodromo ovvero Saggio di alcune invenzioni nuove promesso all' Arte Maestra. His idea, though useless and unpractical in so far that it could never be carried out, is yet deserving of notice, as the principles involved are sound; and this can be said of no earlier attempt. His project was to procure four copper balls of very large dimensions (fig. 1), yet so extremely thin that after the air was exhausted from them they would be lighter than the air they displaced and so would rise; and to those four balls he proposed to attach a boat, with sails, &c., which would carry up a man. He submitted the whole matter to calculation, and proposed that the globes should be about 25 ft. in diameter and 1/225th of an inch in thickness; this would give from all four balls a total ascensional force of about 1200 lb., which would be quite enough to raise the boat, sails, passengers, &c. But the obvious objection to the whole scheme is, that it would be quite impossible to construct a globe of so large a size and of such small thickness which would even support its own weight without collapsing if placed on the ground, much less bear the external atmospheric pressure when the internal air was removed. Lana himself noticed this objection, but he thought that the spherical form of the copper shell would, notwithstanding its extreme thinness, enable it, after the exhaustion was effected, to sustain the enormous pressure, which, acting equally on every point of the surface, would tend to consolidate rather than to break the metal. His proposal to exhaust the air from the globes by attaching to each a tube 36 ft. long, fitted with a stopcock, and so producing a Torricellian vacuum, suggests that he was ignorant of the invention of the air-pump by Otto von Guericke about 1650.

We now come to the invention of the balloon, which was due to Joseph Michel Montgolfier (1740-1810) and Jacques Etienne Montgolfier (1745-1799), sons of Pierre Montgolfier, a large and celebrated papermaker at Annonay, a town about 40 m. from Lyons. The brothers had observed the suspension of clouds in the atmosphere, and it occurred to them that if they could enclose any vapour of the nature of a cloud in a large and very light bag, it might rise and carry the bag with it into the air. Towards the end of 1782 they inflated bags with smoke from a fire placed underneath, and found that either the smoke or some vapour emitted from the fire did ascend and carry the bag with it. Being thus assured of the correctness of their views, they determined to have a public ascent of a balloon on a large scale. They accordingly invited the States of Vivarais, then assembled at Annonay, to witness their aerostatic experiment; and on the 5th of June 1783, in the presence of a considerable concourse of spectators, a linen globe of 105 ft. in circumference was inflated over a fire fed with small bundles of chopped straw. When released it rapidly rose to a great height, and descended, at the expiration of ten minutes, at the distance of about 1 1/2m. This was the discovery of the balloon. The brothers Montgolfier imagined that the bag rose because of the levity of the smoke or other vapour given forth by the burning straw; and it was not till some time later that it was recognized that the ascending power was due merely to the lightness of heated air compared to an equal volume of air at a lower temperature. In this balloon, no source of heat was taken up, so that the air inside rapidly Cooled, and the balloon soon descended.

The news of the experiment at Annonay attracted so much attention at Paris that Barthelemi Faujas de Saint-Fond (1741-1819), afterwards professor of geology at the Musee d'Histoire Naturelle, set on foot a subscription for paying the expense of repeating the experiment. The balloon was constructed by two brothers of the name of Robert, under the superintendence of the physicist, J. A. C. Charles. The first suggestion was to copy the process of Montgolfier, but Charles proposed the application of hydrogen gas, which was adopted. The filling of the balloon, which was made of thin silk varnished with a solution of elastic gum, and was about 13 ft. in diameter, was begun on the 23rd of August 1783, in the Place des Victoires. The hydrogen gas was obtained by the action of dilute sulphuric acid upon iron filings, and was introduced through leaden pipes; but as the gas was not passed through cold water, great difficulty. was experienced in filling the balloon completely; and altogether about 300 lb. of sulphuric acid and twice that amount of iron filings were used (fig. 2). Bulletins were issued daily of the progress of the inflation; and the crowd was so great that on the 26th the balloon was moved secretly by night to the Champ de Mars, a distance of 2 m. On the next day an immense concourse of people covered the Champ de Mars, and every spot from which a view could be ob obtained was crowded. About five o'clock a cannon was discharged as the signal for the ascent, and the balloon when liberated rose to the height of about 3000 ft. with great rapidity. A shower of rain which began to fall directly after it had left the earth in no way checked its progress; and the excitement was so great, that thousands of well-dressed spectators, many of them ladies, stood exposed, watching it intently the whole time it was in sight and were drenched to the skin, The balloon, after remaining in the air for about three-quarters of an hour, fell in a field near Gonesse, about 15 m. off, and terrified the peasantry so much that it was torn into shreds by them. Hydrogen gas was at this time known by the name of inflammable air; and balloons inflated with gas have ever since been called by the people air-balloons, the kind invented by the Montgolfiers being designated fire-balloons. French Writers have also very frequently styled them after their inventors, Charlieres and Montgolfieres. On the 19th of September 1783 Joseph Montgolfier repeated the Annonay experiment at Versailles, in the presence of the king, the queen, the court and an immense number of spectators. The inflation was begun at one o'clock, and completed in eleven minutes, when the balloon rose to the height of about 1500 ft., and descended after eight minutes, at a distance of about 2 m., in the wood of Vaucresson. Suspended below the balloon: in a cage, had been placed a sheep, a cock and a duck, which were thus the first aerial travellers. They were quite uninjured, except the cock, which had its right wing hurt in consequence of a kick it had received from the sheep; but this took place before the ascent. The balloon, which was painted with ornaments in oil colours, had a very showy appearance (fig. 3). Francois Pilatre de Rozier (1756-1785), a native of Metz, who was appointed superintendent of the natural history collections of Louis XVIII. On the 15th of October 1783, and following days, he made several ascents (generally alone, but once with a companion, Girond de Villette) in a captive balloon (i.e. one attached by ropes to the ground), and demonstrated that there was no difficulty in taking up fuel and feeding the fire, which was kindled in a brazier suspended under the balloon, when in the air. The way being thus prepared for aerial navigation, on the 21st of November 1783, Pilatre de Rozier and the marquis d'Arlandes first trusted themselves to a free fire-balloon. The experiment was made from the Jardin du Chateau de la Muette, in the Bois de Boulogne. A large fire-balloon was inflated at about two o'clock, rose to a height of about 500 ft., and passing over the Invalides and the Ecole Mililaire, descended beyond the Boulevards, about 9000 yds. from the place of ascent, having been between twenty and twenty-five minutes in the air. Only ten days later, viz. on the 1st of December 1783, Charles ascended from Paris in a balloon inflated with hydrogen gas. The balloon, as in the case of the small one of the same kind previously launched from the Champ de Mars, was constructed by the brothers Robert, one of whom took part in the ascent. It was 27 ft. in diameter, and the car was suspended from a hoop surrounding the middle of the balloon, and fastened to a net, which covered the upper hemisphere. The balloon ascended very gently from the Tuileries at a quarter to two o'clock, and after remaining for some time at an elevation of about 2000 ft., it descended in about two hours at Nesle, a small town about 27 m. from Paris, when Robert left the car, and Charles made a, second ascent by himself. He had intended to have replaced the weight of his companion by a nearly equivalent quantity of ballast; but not having any suitable means of obtaining such at the place of descent, and it being just upon sunset, he gave the word to let go, and the balloon being thus so greatly lightened, ascended very rapidly to a height of about 2 m. After staying in the air about half an hour, he descended 3 m. from the place of ascent, although he believed the distance traversed, owing to different currents, to have been about 9 m. In this second journey he experienced a violent pain in his right ear and jaw, no doubt produced by the rapidity of the ascent. He also witnessed the phenomenon of a double sunset on the same day; for when he ascended, the sun had set in the valleys, and as he mounted he saw it rise again, and set a second time as he descended.

All the features of the modern balloon as now used are more or less due to Charles, who invented the valve at the top, suspended the car from a hoop, which was itself attached to the balloon by netting, &c. With regard to his use of hydrogen gas, there are anticipations that must be noticed. As early as 1766 Henry Cavendish showed that this gas was at least seven times lighter than ordinary air, and it immediately occurred to Dr Joseph Black, of Edinburgh, that a thin bag filled with hydrogen gas would rise to the ceiling of a room. He provided, accordingly, the allantois of a calf, with the view of showing at a public lecture such a curious experiment; but for some reason it seems to have failed, and Black did not repeat it, thus allowing a great discovery, almost within his reach, to escape him. Several years afterwards a similar idea occurred to Tiberius Cavallo, who found that bladders, even when carefully scraped, are too heavy, and that China paper is permeable to the gas. But in 1782, the year before the invention of the Montgolfiers, he succeeded in elevating soap-bubbles by inflating them with hydrogen gas. Researches on the use of gas for inflating balloons seem to have been carried on at Philadelphia nearly simultaneously with the experiments of the Montgolfiers; and when the news of the latter reached America, D. Rittenhouse and F. Hopkinson, members of the Philosophical Society at Philadelphia; constructed a machine consisting of forty-seven small hydrogen gas-balloons attached to a car or cage. After several preliminary experiments, in which animals were let up to a certain height by a rope, a carpenter, one James Wilcox, was induced to enter the car for a small sum of money; the ropes were cut, and he remained in the air about ten minutes, and only then effected his descent by making incisions in a number of the balloons, through fear of falling into the river, which he was approaching.

First Ascents in Great Britain.

Although the news of the Annonay and subsequent experiments in France rapidly spread all over Europe, and formed a topic of general discussion, still it was not till five months after the Montgolfiers had first publicly sent a balloon into the air that any aerostatic experiment was made in England. In November 1783 Count Francesco Zambeccari (1756-1812), an Italian who happened to be in London, made a balloon of oil-silk, 10 ft. in diameter, and weighing 11 lb. It was publicly shown for several days, and on the 25th it was three-quarters filled with hydrogen gas and launched from the Artillery ground at one o'clock. It descended after two hours and a half near Petworth, in Sussex, 48 m. from London. This was the first balloon that ascended from English ground. On the 22nd of February 1784 a hydrogen gas balloon, 5 ft. in diameter, was let up from Sandwich, in Kent, and descended at Warneton, in French Flanders, 75 m. distant. This was the first balloon that crossed the Channel. The first person who rose into the air from British ground appears to have been J. Tytler1, who ascended from the Comely Gardens, Edinburgh, on the 27th of August 1784, in a fire-balloon of his own construction. He descended on the road to Restalrig, about half a mile from the place where he rose.

But it was Vincent Lunardi who practically introduced aerostation into Great Britain. Although Tytler had the precedence by a few days still his attempts and partial success were all but unknown; whereas Lunardi's experiments excited an enormous amount of enthusiasm in London. He was secretary to Prince Caramanico, the Neapolitan ambassador, and his published letters to his guardian, the chevalier Compagni, written while he was carrying out his project, and detailing all the difficulties, &c., he met with as they occurred, give an interesting and vivid account of the whole matter. His balloon was 33 ft. in circumference (fig.4), and was exposed to the public view at the Lyceum in the Strand, where it was visited by upwards of 20,000 people. He originally intended to ascend from Chelsea Hospital, but the conduct of a crowd at a garden at Chelsea, which destroyed the fire-balloon of a Frenchman named de Moret, who announced an ascent on the 11th of August, but was unable to keep his word, led to the withdrawal of the leave that had been granted. Ultimately he was permitted to ascend from the Artillery ground, and on the 15th of September 1784 the inflation with hydrogen gas took place. It was intended that an English gentleman named Biggin should accompany Lunardi; but the crowd becoming impatient, the latter judged it prudent to ascend with the balloon only partially full rather than risk a longer delay, and accordingly Mr Biggin was obliged to leave the car. Lunardi therefore ascended alone, in presence of the prince of Wales and an enormous crowd of spectators. He took up with him a pigeon, a dog and a cat, and the balloon was provided with oars, by means of which he hoped to raise or lower it at pleasure. Shortly after starting the pigeon escaped, and one of the oars became broken and fell to the ground. In about an hour and a half he descended at South Mimms, in Hertfordshire, and landed the cat, which had suffered from the cold: he then ascended again, and descended, after the lapse of about three-quarters of an hour, at Standon, near Ware, where he had great difficulty in inducing the peasants to come to his assistance; but at length a young woman, taking hold of one of the cords, urged the men to follow her example, which they then did. The excitement caused by this ascent was immense, and Lunardi at once became the star of the hour. He was presented to the king, and was courted and flattered on all sides. To show the enthusiasm displayed by the people during his ascent, he tells himself, in his sixth letter, how a lady, mistaking the oar which fell for himself, was so affected by his supposed destruction that she died in a few days; but, on the other hand, he says he was told by the judges "that he had certainly saved the life of a young man who might possibly be reformed, and be to the public a compensation for the death of the lady''; for the jury were deliberating on the fate of a criminal, whom they must ultimately have condemned, when the balloon appeared, and to save time they gave a verdict of acquittal, and the whole court came out to view the balloon. The king also was in conference with his ministers; but on hearing that the balloon was passing, he broke up the discussion, and with them watched the balloon through telescopes. The balloon was afterwards exhibited in the Pantheon. In the latter part of the following year (1785) Lunardi made several successful ascents from Kelso, Edinburgh and Glasgow (in one of which he traversed a distance of 110 m.); these he described in a second series of letters. The first ascent from Ireland was made on the 19th of January 1785 by a Mr Crosbie, who on the following 19th of July attempted to cross St George's Channel to England but fell into the sea. The second person who ascended from Ireland was Richard Maguire. Mr Crosbie had inflated his balloon on the 12th of May 1785, but it was unable to take him up. Maguire in these circumstances offered himself as a substitute, and his offer being accepted he made the ascent. For this he was knighted by the Lord-Lieutenant. Another attempt to cross St George's Channel was made by James Sadler on the 1st of October 1812, and he had nearly succeeded when in consequence of a change of wind he was forced to descend into the sea off Liverpool, whence he was rescued by a fishing-boat. But on the 22nd of July 1817 his second son, Windham Sadler, succeeded in crossing from Dublin to Holyhead.

The first balloon voyage across the English Channel was accomplished by Jean Pierre Blanchard (1753-1809) and Dr. J. Jeffries, an American physician, on the 7th of January 1785. In the preceding year, on the 2nd of March, Blanchard, who was one of the most celebrated of the earlier aeronauts, made his first voyage from Paris in a balloon 27 ft. in diameter (fig. 5), and descended at Billancourt near Sevres. Just as the balloon was about to start, a young man jumped into the car and drawing his sword declared his determination to ascend with Blanchard. He was ultimately removed by force. It has sometimes been incorrectly stated that he was Napoleon Bonaparte; his name in reality was Dupont de Chambon. In their Channel crossing Blanchard and his companion, who started from Dover, when about one-third across found themselves descending, and threw out every available thing from the boat or car. When about three- quarters across they were descending again, and had to throw out not only the anchor and cords, but also to strip and throw away their clothing, which they found they were rising, and their last resource, viz. to cut away the car, was rendered unnecessary. As they approached the shore the balloon rose, describing a magnificent arch high over the land. They descended in the forest of Guinnes. On the 15th of June 1785, Pilatre de Rozier made an attempt to repeat the exploit of Blanchard and Jeffries in the reverse direction, and cross from Boulogne to England. For this purpose he contrived a double balloon, which he expected would combine the advantages of both kinds—-a fire-balloon, 10 ft. in diameter, being placed underneath a gas-balloon of 37 ft. in diameter, so that by increasing or diminishing the fire in the former it might be possible to ascend or descend without waste of gas. Rozier was accompanied by P. A. Romain, and for rather less than half an hour after the aerostat ascended all seemed to be going on well, when suddenly the whole apparatus was seen in flames, and the unfortunate adventurers came to the ground from the supposed height of more than 3000 ft. Rozier was killed on the spot, and Romain only survived about ten minutes. A monument was erected on the place where they fell, which was near the sea-shore, about 4 m. from the starting-point.

Early large balloons.

The largest balloon on record (if the contemporary accounts are correct) ascended from Lyons on the 19th of January 1784. It was more than 100 ft. in diameter, about 130 ft. in height, and when distended had a capacity, it is said, of over half a million cubic feet. It was called the "Flesselles'' (from the name of its proprietor, we believe), and after having been inflated from a straw fire in seventeen minutes, it rose with seven persons in the car to the height of about 3000 ft., but descended again after the lapse of about a quarter of an hour from the time of starting, in consequence of a rent in the upper part. Another large fire-balloon, 68 ft. in diameter, was constructed by the chevalier Paul Andreani of Milan, and on the 25th of February he ascended in it from Milan, remaining in the air for about twenty minutes. This is usually regarded as the first ascent in Italy (but see Monck Mason's Aeronautica, p. 247). On the 7th of November 1836, at half-past one o'clock, a large balloon containing about 85,000 cub. ft. of gas ascended from Vauxhall Gardens, London, carrying Robert Hollond, M.P., Monck Mason and Charles Green, and descended about two leagues from Weilburg, in the duchy of Nassau, at half-past seven the next morning, having thus traversed a distance of about 500 m. in 18 hours; Liege was passed in the course of the night, and Coblentz in the early morning. In consequence of this journey the balloon became famous as the "Nassau Balloon'' (fig. 6). Charles Green (1785-1870), who constructed it and subsequently became its owner, was the most celebrated of English aeronauts, and made an extraordinary number of ascents. His first, made from the Green Park, London, on the 19th of July 1821 at the coronation of George IV., was distinguished for the fact that for the first time coal-gas was used instead of hydrogen for inflating the balloon. In 1828 he made an equestrian ascent from the Eagle Tavern, City Road, London, seated on his favourite pony. Such ascents have since been repeated; in 1852 Madame Poitevin made one from Cremorne Gardens, but was prevented from giving a second performance by police interference, the exhibition outraging public opinion. It was in descending from the "Nassau Balloon'' in a parachute that Robert Cocking was killed in 1837 (see PARACHUTE) . Green was the inventor of the guide-rope, which consists of a long rope trailing below the car. Its function is to reduce the waste of gas and ballast required to keep the balloon at a proper altitude. When a balloon sinks so low that a good deal of the guide-rope rests on the ground, it is relieved of so much weight and therefore tends to rise; if on the other hand it rises so that most of the rope is lifted off the ground, it has to bear a greater weight and tends to sink.

In 1863 A. Nadar, a Paris photographer, constructed "Le Geant,'' which was the largest gas-balloon made up to that time and contained over 200,000 cub. ft. of gas. Underneath it was placed a smaller balloon, called a compensator, the object of which was to prevent loss of gas during the voyage. The car had two stories, and was, in fact, a model of a cottage in wicker-work, 8 ft. in height by 13 ft. in length, containing a small printing-office, a photographic department, a refreshment-room, a lavatory, &c. The first ascent took place at five o'clock on Sunday the 4th of October 1863, from the Champ de Mars. There were thirteen persons in the car, including one lady, the princess de la Tour d'Auvergne, and the two aeronauts Louis and Jules Godard. In spite of the elaborate preparations that had been made and the stores of provisions that were taken up, the balloon descended at nine o'clock, at Meaux, the early descent being rendered necessary, it was said, by an accident to the valve-line. At a second ascent, made a fortnight later, there were nine passengers, including Madame Nadar. The balloon descended at the expiration of seventeen hours, near Nienburg in Hanover, a distance of about 400 m. A strong wind was blowing, and it was dragged over the ground for 7 or 8 m. All the passengers were bruised, and some seriously hurt. The balloon and car were then brought to England, and exhibited at the Crystal Palace at the end of 1863 and beginning of 1864. The two ascents of Nadar's balloon excited an extraordinary amount of enthusiasm and interest, vastly out of proportion to what they were entitled to. Nadar's idea was to obtain sufficient money, by the exhibition of his balloon, to carry out a plan of aerial locomotion he had conceived possible by means of the principle of the screw; in fact, he spoke of "Le Geant'' as "the last balloon.'' He also started L'Aeronaute, a newspaper devoted to aerostation, and published a small book, which was translated into English under the title The Right to Fly. Directly after Nadar's two ascents, Eugene Godard constructed a fire-balloon of nearly half a million cubic feet capacity—more than double that of Nadar's and only slightly less than that attributed to the "Flesselles'' of 1783. The air was heated by an 18-ft. stove, weighing, with the chimney, 980 lb. This furnace was fed by straw; and the "car'' consisted of a gallery surrounding it. Two ascents of this balloon, the first fire-balloon seen in London, were made from Cremorne Gardens in July 1864. After the first journey the balloon descended at Greenwich, and after the second at Walthamstow, where it was injured by being blown against a tree. Notwithstanding its enormous size, Godard asserted that it could be inflated in half an hour, and the inflation at Cremorne did not occupy more than an hour. In spite of the rapidity with which the inflation was effected, few who saw the ascent could fail to receive an impression unfavourable to the fire-balloon in the matter of safety, as a rough descent, with a heated furnace as it were in the car, could not be other than most dangerous.

Long balloon voyages.

In the summer of 1873 the proprietors of the New York Daily Graphic, reviving a project discussed by Green in 1840, determined to construct a very large balloon, and enable the American aeronaut, John Wise, to realize his favourite scheme of crossing the Atlantic Ocean to Europe, by taking advantage of the current from west to east which was believed by many to exist constantly at heights above 10,000 ft. The project came to nothing owing to the quality of the material of which the balloon was made. When it was being inflated in September 1873 a rent was observed after 325,000 cub. ft. of gas had been put in, and the whole rapidly collapsed. The size was said to be such as to contain 400,000 cub. ft., so that it would lift a weight of 14,000 lb. No balloon voyage has yet been made of a length comparable to the breadth of the Atlantic. In fact only two voyages exceeding 1000 m. are on record—that of John Wise from St Louis to Henderson, N.Y., 1120 m., in 1859, and that of Count Henry de la Vaulx from Paris to Korosticheff in Russia, 1193 m., in 1900. On the 11th of July 1897 Salomon Andree, with two companions, Strendberg and Frankel, ascended from Spitzbergen in a daring attempt to reach the North Pole, about 600 m. distant. One carrier pigeon, apparently liberated 48 hours after the start, was shot, and two floating buoys with messages were found, but nothing more was heard of the explorers.

Scientific Ascents.

At an early date the balloon was applied to scientific purposes. as far back as 1784, Dr Jeffries made an ascent from London in which he carried out barometric, thermometric and hygrometric observations, also collecting samples of the air at different heights. In 1803 the St Petersburg Academy of Sciences, entertaining the opinion that the experiments made on mountain-sides by J. A. Deluc, H. B. de Saussure, A. von Humboldt and others must give results different from those made in free air at the same heights, resolved to arrange a balloon ascent. Accordingly, on the 30th of January 1808, .Sacharof, a member of the academy, ascended in a gas balloon, in company with a French aeronaut, E. G. Robertson, who at one time gave conjuring entertainments in Paris. The ascent was made at a quarter past seven, and the descent effected at a quarter to eleven. The height reached was less than 1 1/2 m. The experiments were not very systematically made, and the chief results were the filling and bringing down of several flasks of air collected at different elevations, and the supposed observation that the magnetic dip was altered. A telescope fixed in the bottom of the car and pointing vertically downwards enabled the travellers to ascertain exactly the spot over which they were floating at any moment. Sacharof found that, on shouting downwards through his speaking-trumpet, the echo from the earth was quite distinct, and at his height was audible after an interval of about ten seconds (Phil. Mag., 1805, 21, p. 193).

Some of the results reported by Robertson appearing doubtful, Laplace proposed to the members of the French Academy of Sciences that the funds placed by the government at their disposal for the prosecution of useful experiments should be utilized in sending up balloons to test their accuracy. The proposition was supported by J. A. C. Chaptal, the chemist, who was then minister of the interior, and accordingly the necessary arrangements were speedily effected, the charge of the experiments being given to L. J. Gay-Lussac and J. B. Biot. The principal object of this ascent was to determine whether the magnetic force experienced any appreciable diminution at heights above the earth's surface. On the 24th of August 1804, Gay-Lussac and Biot ascended from the Conservatoire des Arts at ten o'clock in the morning. Their magnetic experiments were incommoded by the rotation of the balloon, but they found that, up to the height of 13,000 ft., the time of vibration of a magnet was appreciably the same as on the earth's surface. They found also that the air became drier as they ascended. The height reached was about 13,000 ft., and the temperature declined from 63 deg. to 51 deg. F. The descent was effected about half-past one, at Meriville, 18 leagues from Paris.

In a second experiment, which was made on the 16th of September 1804, Gay-Lussac ascended alone. The balloon left the Conservatoire des Arts at 9.40 A.M., and descended at 3.45 P.M. between Rouen and Dieppe. The chief result obtained was that the magnetic force, like gravitation, did not experience any sensible variation at heights from the earth's surface which we can attain to. Gay-Lussac also brought down air collected at the height of nearly 23,000 ft., and on analysis it appeared that its composition was the same as that of air collected at the earth's surface. At the time of leaving the earth the thermometer stood at 82 deg. F., and at the highest point reached (23,000 ft.) it was 14.9 deg. F. Gay-Lussac remarked that at his highest point there were still clouds above him.

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