At

foyaites include the greater number of known nepheline-syenites | closely linked to the phonolites and pass into them by various and are called after Foya in the Serra de Monchique (southern gradations. They are usually richer in alkalis and silica and Portugal), from which they were first described. They are grey, green or reddish, and mostly of massive structure with preponderat contain less iron, lime and magnesia than the basanites and ing potash felspar, some nepheline, and a variable (often small) nepheline-basalts, a difference which finds expression in the amount of femic minerals. Pyroxene-, hornblende- and biotite presence of olivine and the smaller amount of felspars and foyaites have been recognized according to their mineral com- felspathoids in the latter. position. Examples of the first-named occur in southern Norway with the laurdalites; they contain aegirine and black mica. Alnö Island in the Gulf of Bothnia (Sweden) similar rocks are found bearing enclosures or altered limestone with wollastonite and scapolite. In Siebenburgen (Hungary) there is a well-known rock of this group, very rich in microcline, blue sodalite and cancrinite. It contains also orthoclase, nepheline, biotite, aegirine, acmite, &c. To this type the name ditroite has been given from the place where it occurs (Ditro). Pyroxene-foyaite has been described also from Pouzac in the Pyrenees (S. France). Mica-foyaite is not very common, but is known at Miask in the Ural Mountains (miaskite); where it is coarse-grained, and contains black mica, sodalite and cancrinite. The hornblende-foyaites are usually brown or blue, and intensely dichroic, but may contain also biotite or augite. Rocks of this class occur in Brazil (Serra de Tingua) containing sodalite and often much augite, in the western Sahara and Cape Verde Islands; also at Zwarte Koppies in the Transvaal, Madagascar, São Paulo (in Brazil), Paisano Pass (West Texas) and Montreal, Canada. The rock of Salem, Mass., U.S.A., is a mica-foyaite rich in albite and aegirine; it accompanies granite and essexite.

Litchfieldite is another well-marked type of nepheline-syenite, in which albite is the dominant felspar. It is named after Litch field, Maine, U.S.A., where it occurs in scattered blocks. Biotite, cancrinite and sodalite are characteristic of this rock. A similar nepheline-syenite is known from Hastings Co., Ontario, and contains hardly any orthoclase, but only albite felspar. Nepheline is very abundant and there is also cancrinite, sodalite, scapolite, calcite, biotite and hornblende. The lujaurites are distinguished from the rocks above described by their dark colour, which is due to the abundance of minerals such as augite, aegirine, arfvedsonite and other kinds of amphibole. Typical examples are known near Lujaur on the White Sea, where they occur with umptekites and other very peculiar rocks. Other localities for this group are at Julianehaab in Greenland (with sodalite-syenite); at their margins they contain pseudomorphs after leucite. The lujaurites frequently have a parallel-banding or gneissose structure. Sodalite-syenites in which sodalite very largely or completely takes the place of nepheline occur in Greenland, where they contain also microcline-perthite, aegirine, arfvedsonite and eudialyte. Cancrinite-syenite, with a large percentage of cancrinite, has been described from Dalekarlia (Sweden) and from Finland. We may also mention urtite from Lujaur Urt on the White Sea, which consists very largely of nepheline, with aegirine and apatite, but no felspar. Jacupirangite (from Jacupiranga in Brazil) is a blackish rock composed of titaniferous augite, magnetite, ilmenite, perofskite and nepheline, with secondary biotite.

The chemical peculiarities of the nepheline-syenites are well marked, as will be seen from the following analyses. They are exceedingly rich in alkalis and in alumina (hence the abundance of felspathoids and alkali felspars) with silica varying from 50 to 56%, while ime, magnesia and iron are never present in great quantity, though somewhat more variable than the other components. As a group, also, these rocks have a low specific gravity.

CaO.|MgO. | K2O. | NagO. 3.15 1.98 4.84 7.67 1.99 0.69 0-13 6-79 9-28 0.42 0.32 0.13 4.77 8.44 3.28 1-85 0-83 5.25 9.87 (J. S. F.) NEPHELINITES. The group of effusive rocks which contains nepheline with plagioclase felspar is subdivided into nephelinetephrites and nepheline-basanites, while those which contain nepheline but not felspar are nephelinites and nepheline-basalts. The tephrites differ from the basanites in the absence of olivine, and the same distinction subsists between the nephelinites and nepheline-basalts.

The nepheline is colourless and transparent when fresh, often in six-sided prisms, but also as irregular interstitial masses filling the spaces between the other minerals, and hard to identify owing to its low double refraction and frequent decomposition. Leucite appears in some tephrites; haüyne is more frequent as small dodecahedra often filled with black inclusions. The augite varies a good deal, being bright green or dark green (aegirine) and rich in soda in some tephrites and nephelinites, while in basanites and basalts it is often brown basaltic augite or purple "titaniferous" augite. It has often good crystalline form, and occurs as eight-sided monoclinic prisms, but the soda augites may be of late crystallization and form mossy or irregular growths in the matrix. Brown hornblende is much less common, and a red biotite is very characteristic of certain nephelinites. Of the felspars, labradorite is probably the most common, with more acid varieties of plagioclase. Sanidine is by no means absent, but may be considered as an accessory. The olivine presents no peculiarities. Melilite, perofskite, pseudobrookite, melanite garnet, iron oxides, apatite and chromite are occasionally met with.

All these rocks are practically confined to lavas of Tertiary and recent age, though some occur as dikes or small intrusive masses. The plutonic facies of these rocks are found among the theralites, shonkinites, essexites and ijolites. In the British Isles they are exceedingly scarce, though nepheline-basanite occurs in a dike which is presumably Tertiary, cutting the Triassic rocks at Butterton in Staffordshire, and nepheline-basalt has been found in a single neck at John o' Groat's in Caithness and at one or two places near North Berwick in Haddingtonshire. They attain a great development in the Canary Islands (Teneriffe, Grand Canary, &c.) and in the Azores, Cape Verde Islands and Fernando Noronha. In Germany they are represented among the Tertiary eruptive rocks of the Rhine district and Thuringia, at the extinct craters of the Eiffel and at the Kaiserstuhl. In central Bohemia there are many occurrences of nepheline-tephrites, basanites and basalts which though fine grained contain all their minerals in excellent preservation. The nephelinite of Katzenbuckel in the Odenwald is well known. Contrasted with the phonolites and leucitophyres these rocks are scarce in Italy and the Mediterranean province, but leucite-bearing nepheline-tephrites occur at Monte Vulture and nepheline-basalts in Tripoli. In America these rocks occur in Texas, in the Bearpaw Mountains of Montana and at Cripple Creek, Colorado. From Argentina some members have been described: thay have a great extension in East Africa (Somaliland and Masai-land) and occur also in North Nigeria. A few also have been described from New South Wales, New Zealand (Dunedin) and Tasmania. (J. S. F.)

"de

NEPHEW, the son of a brother or sister. The word is adapted from Fr. neveu, Lat. nepos (originally "grandson" or scendant "). The O. Eng. nefa survived in the form neve till the 15th century; this represents the Teutonic branch, cf. Ger. Neffe, Dutch neef; the ultimate root is seen in the cognate Gr. νέποδες, descendants," ȧvefiós, "kinsman," and Sans. napál, napt, "descendants " or "descendant." The correlative niece," the daughter of a brother or sister, is from Fr. nièce, cf. Ger. Nichte. A euphemistic use of "nephew " is that of the Lat. neptis, the feminine form of nepos; the O. Eng. word was nift, natural son of a pope, cardinal or other ecclesiastic; and from the practice of granting preferments to such children the word nepotism " is used of any favouritism shown in finding positions for a man's family.

64

NEPI (anc. Nepet or Nepete), a town and episcopal see of Italy, in the province of Rome, 7 m. S.W. of the town of Civita Lavas with nepheline, plagioclase and augite = nepheline-Castellana, 738 ft. above sea-level. Pop. (1901) 2973. The site, tephrites.

Lavas with nepheline, plagioclase, augite and olivine-nepheline

basanites.

Lavas with nepheline and augite nephelinites.

Lavas with nepheline, augite and olivine = nepheline-basalts. In their essential and accessory minerals, appearance and structure, these rocks have much in common, and they tend to occur in a natural association as basic rocks comparatively rich in alkalis and alumina. The nephelinites and tephrites are rather

surrounded by ravines and accessible only on the W., is naturally strong and characteristic of an Etruscan town; on this side there is a considerable fragment of the ancient Etruscan wall, built of rectangular blocks of tufa (whether the rest of the site was protected by walls is uncertain), and a ruined castle, erected by Antonio da Sangallo the elder in 1499, for Pope Alexander VI., and restored by Pope Paul III. The municipio (town hall) is from the designs of Vignola, and contains some ancient

inscriptions. The cathedral was burnt down by the French in 1789 | many errors (especially in chronology), but supply information and restored in 1831. A mile and a half E.N.E. is the Romanesque church of S Elia, founded about A.D. 1000, with frescoes of the period. It contains a pulpit of the time of Pope Gregory IV. (827-844), the sculptures of which are scattered about the church (F. Mazzanti in Nuovo Bollettino d'Archaeologia Cristiana, 1896, 34).

planets or satellites of the solar system. The most noteworthy feature | Uranian planet, the existence of which was made probable by connected with the satellite is a secular change which is going on in the disagreement between the older and more recent observations.2 the position of its orbital plane. Were the planet spherical in form, no such change could occur, except an extremely slow one produced In 1838 Airy showed in a letter to the Astronomische Nachby the action of the sun. The change is therefore attributed to a richten that not only the heliocentric longitude, but the tabulated considerable ellipticity of the planet, which is thus inferred to be in radius vector of Uranus was largely in error, but made no rapid rotation. It will ultimately be possible to determine from this motion the position of the axis of rotation of Neptune with much suggestions as to the cause.3 greater precision than it could possibly be directly observed. The following elements of the satellite were determined by H. Struve from all the observations available up to 1892:

The longitude of the actual planet was 327° 57' on the 1st of
October 1846.

The close agreement of these elements led Airy to suggest to Challis, on the 9th of July 1846, a search for the planet with the Northumberland telescope. He proposed an examination of a part of the heavens 30° long in the direction of the ecliptic and to broad, and estimated the number of hours' work likely to be employed in this sweep. The proposed sweeps were commenced by Challis on the 29th of July. The plan required each region to be swept through twice, and the positions of all the known stars found to be compared, in order that the position of the planet might be detected by its motion. On the 31st of August Leverrier's concluding paper was presented to the French Academy, and on the 18th of September he wrote to John G. Galle (1812-1910), then chief assistant at the Berlin observatory, suggesting that he should search for the computed planet, with the hope of detecting it by its disk, which was probably more than 3" in diameter. This letter, probably received on the 23rd of September, was communicated to J. F. Encke, the director of the observatory, who approved of the search. H. L. d'Arrest, a student living at the observatory, expressed a wish to assist. In the evening the search was commenced, but it was not found possible to detect any planet by its disk. Star charts were at the time being prepared at the observatory under the auspices of the Berlin Academy of Sciences. It was suggested by d'Arrest that this region might be covered by one of the charts. Referring to the chart, which was lying in a drawer, it was found that such was the case. Comparing the stars on the chart one by one with the heavens it was found that an eighth magnitude star now visible was not on the chart. This object was observed until after midnight, but no certain motion was detected. On the following evening the object was again looked for, and found to have actually moved. The existence of the planet was thus established. It was afterwards found that Challis in his sweeps had observed the planet on the 4th of August, but, not having compared his observations with those made subsequently, had failed to detect it.

The question whether Leverrier should receive the sole credit of the discovery was warmly discussed. Arago took the extreme ground that actual publication alone should be considered, rejecting Adams's communications to Airy and Challis as quite unworthy of consideration. He also suggested that the name of Leverrier should be given to the planet, but this proposal was received with so little favour outside of France that he speedily withdrew it, proposing that of Neptune instead.

This

The observations of the first opposition enabled Sears Cook Walker of the National Observatory, Washington, in February 1847 to compute the past positions of the planet, and identify it with a star observed by Lalande at Paris in May 1795. being communicated to the Paris observatory, an examination of Lalande's manuscript showed that he had made two observations of the planet, on the 8th and 10th of May, and finding them discordant had rejected one as probably in error, and marked the other as questionable. A mere re-examination of the region to see which observation was in error would have led him to the discovery of the planet more than half a century before it was actually recognized. The identity of Lalande's star with Neptune was also independently shown by Petersen of Altona, before any word of Walker's work had reached him. BIBLIOGRAPHY.-The principal sources for the history of the discovery of Neptune are the Astronomische Nachrichten, vols. xxv., xxvi., xxviii., and Lindenau's paper in the Ergänzungsheft to this Astronomical Society, vol. xvi., Airy gave a detailed history of the publication, pp. 1-31 (Altona, 1849). In the Memoirs of the Royal circumstances connected with the discovery, so far as he was cognizant of them. Documents pertaining to the subject are found in the Monthly Notices of the Royal Astron. Society. B. A. Gould, Report to the Smithsonian Institution on the History of the Discovery of Neptune, published by the Smithsonian Institution (Washington, 1850), is the most complete and detailed history of all the circumstances connected with the discovery, and with the early investigations on the orbit of the planet, that has been published. Leverrier's naissance des temps, and Adams's as an appendix to the Nautical investigation was published in extenso as an addition to the ConAlmanac for 1851. Peirce's discussions, so far as published at all, are found in the Proceedings of the American Academy of Arts and Sciences. The first computations of the orbit after the discovery were made by Scars Cook Walker, and published by the Smithsonian Institution (1848-1850). General tables of the motion of Neptune are in Kowalski's Tables du mouvement de la planète Neptune; Newcomb's Investigation of the Orbit of Neptune, Washington, Smithsonian Institution (1866); Leverrier's Annales de l'Observatoire de Paris; Astron. Papers of the American Ephemeris, vol. vii., part iv. Tables Memoirs, vol. xiv. (1877), and lastly Newcomb's "Tables" in of the satellite are found in Newcomb, The Uranian and Neptunian Systems; appendix to the Washington observations for 1873(S. N.) NÉRAC, a town of south-western France, capital of an arrondissement in the department of Lot-et-Garonne, 16 m. W.S.W of Agen by road. Pop. (1906) town, 4018; commune, 6318. The town, once the capital of the dukes of Albret, is divided by the Baise into two parts, Grand-Nérac on the left bank and Petit-Nérac on the right bank. The river is spanned by a bridge of the 16th century, called the Pont Vieux, and by the Pont Neuf, of modern construction. Narrow winding streets often bordered by old houses ascend from the narrow quays on both banks. From the left bank a staircase leads to the Rue Henri Quatre, where stands a wing of the castle in which Henry IV. former palace of the Chambre des Comptes is now occupied by the tribunal of commerce, the library and the muscum. The church of Grand-Nérac of the 18th century and the church of Petit-Nérac of the 19th century offer no remarkable features. On the left bank of the Baise, above Grand-Nérac, market gardens have taken the place of the old gardens of the Sires d'Albret, but remains of the Palais des Mariannes and of the Pavillon des Bains du Roi de Navarre, both of Renaissance architecture, are left. The famous promenade of La Garenne laid out by Antoine de Bourbon, king of Navarre, stretches for more than a mile along the opposite bank of the river. The remains of a Roman villa, including a fragment of mosaic, have been found there. A road leads from the south end of La Garenne to the ruins of the feudal castle of Nazareth. The Château du Tasta of the 15th century is within a short distance of Nérac. The town has a sub-prefecture, and the industries include brewing and cork-working.

The observations at the first opposition showed that the planet was moving in a nearly circular orbit, and was at a mean distance from the sun much less than that set by Leverrier as the smallest possible. The latter had in fact committed the error of deter-lived. A statue of the king stands in one of the squares. The mining the limits by considering the variations of the elements one at a time, assuming in the case of each that while it varied the others remained constant. But a simultaneous variation of all the elements would have shown that the representation of the observations of Uranus would be improved by a simultaneous diminution of both the eccentricity and the mean distance, the orbit becoming more nearly circular and the planet being brought nearer to the sun. But this was not at first clearly seen, and Benjamin Peirce of Harvard University went so far as to maintain that there was a discontinuity between the solution of Adams and Leverrier and the solution offered by the planet itself, and that the coincidence in direction of the actual and computed planet was an accident. But this view was not well founded, and the only explanation needed was to be found in Leverrier's faulty method of determining the limits within which the planet must be situated. As a matter of fact the actual motion of the planet during the century preceding, as derived from Leverrier's elements, was much nearer the truth than the elements themselves were. This arose from the fact that his very elliptic orbit, by its large eccentricity, brought the planet near to the sun, and therefore near to its true position, during the period from 1780 to 1845, when the action on Uranus was at its greatest.

Nérac appears at the beginning of the 11th century as a possession of the monks of St Pierre de Condom. The lords of Albret gradually deprived them of their authority over the town, and at the beginning of the 14th century founded a castle on the left bank of the Baise. In the 16th century the castle was the residence of Henry IV. during much of his youth and of

Marguerite de Valois, sister of Francis I., of Jeanne d'Albret, | in 1851, of Chita, the present capital of Transbaikalia, Nerchinsk and of the second Marguerite de Valois, wife of Henry IV., has been falling into decay. who held a brilliant court there. Nérac, the inhabitants of which had adopted the Reformed religion, was seized by the Catholics in 1562. The conferences, held there at the end of 1578 between the Catholics and Protestants, ended in February 1579 in the peace of Nérac. In 1580 the town was used by Henry IV. as a base for attacks on the Agenais, Armagnac and Guienne. A Chambre de l'Edit for Guienne and a Chambre des Comptes were established there by Henry IV. In 1621, however, the town took part in the Protestant rising, was taken by the troops of Louis XIII. and its fortifications dismantled. Soon after it was deprived both of the Chambre de l'Edit and of the Chambre des Comptes, and its ruin was completed by the revocation of the Edict of Nantes in 1685.

The fort of Nerchinsk dates from 1654, and the town was NERGAL, the name of a solar deity in Babylonia, the main founded in 1658 by Pashkov, who in that year opened direct seat of whose cult was at Kutha or Cuthah, represented by the communication between the Russian settlements in Transbaikalia mound of Tell-Ibrahim. The importance of Kutha as a religious and those on the Amur which had been founded by Cossacks and and at one time also as a political centre led to his surviving the fur-traders coming from the Yakutsk region. In 1689 was signed tendency to concentrate the various sun-cults of Babylonia in between Russia and China the treaty of Nerchinsk, which Shamash (q.v.). He becomes, however, the representative of stopped for two centuries the farther advance of the Russians into a certain phase only of the sun and not of the sun as a whole. the basin of the Amur. After that Nerchinsk became the chief Portrayed in hymns and myths as a god of war and pestilence, centre for the trade with China. The opening of the western there can be little doubt that Nergal represents the sun of noonroute through Mongolia, by Urga, and the establishment of a time and of the summer solstice which brings destruction to mancustom-house at Kiakhta in 1728 diverted this trade into a new kind. It is a logical consequence that Nergal is pictured also as the channel. But Nerchinsk acquired fresh importance from the deity who presides over the nether-world, and stands at the head influx of immigrants, mostly exiles, into eastern Transbaikalia, of the special pantheon assigned to the government of the dead, the discovery of rich mines and the arrival of great numbers of who are supposed to be gathered in a large subterranean cave convicts, and ultimately it became the chief town of Trans-known as Arâlu or Irkalla. In this capacity there is associated baikalia. In 1812 it was transferred from the banks of the Shilka with him a goddess Allatu, though there are indications that at to its present site, on account of the floods. Since the foundation, one time Allatu was regarded as the sole mistress of Arâlu, ruling