HEPTUNUB. 



NEURALGIA. 



24 



iU discovery wu the remit of a happy accident ! But any mich diffi- 

 culty will vanish when it is lrne in mind that the object proposed 

 by M. La Verrier and Mr. Adami wu not to determine rigorously the 

 ismsnts of the disturbing planet, which could only result from the 

 (ItXMsinn of a series of its observed positions, but merely to ascertain 

 its whereabouts during the period when its perturbations were sensible. 

 For this purpose, any combination of elements varying within consider- 

 able limits wiU.be sufficient. I luring the whole of the period comprised 

 between the year IfiBO and the beginning of the present century, the 

 disturbing action of Neptune was incapable of exercising any appre- 

 ciable influence on the motion of Uranus. During the present 

 century, however, the perturbations have been of sensible magnitude. 

 It was therefore necessary that throughout this period the intensity 

 and direction of the disturbing force, and consequently the position 

 of the disturbing body, should be represented with considerable 

 precision by the theoretical results of M. Le Verrier and Mr. Adams. 

 That this object was effected by both of the geometers just mentioned 

 may I e readily seen by the following numbers, which exhibit a 

 comparison between the heliocentric longitude and radius vector of 

 Neptune for every ten years since the year 1800, and the corresponding 

 values of the co-ordinates, as deducible from the researches of M. 

 Le Verrier and Mr. Adams : 



Shortly after the discovery of Neptune, Mr. Lassell discovered that it 

 was attended by a satellite. M. Otto Struve found from his own obser- 

 vations, made with the great refractor of Pulkowa, that the semi -major 

 axis of its apparent orbit is 1 7""89, and that it revolves round the planet 

 in a period of 5* 21 15". These elements give for the mass of the planet 

 the value If J. n , the sun's mass being represented by unity. Professor 

 Peirce, of Harvard College, Cambridge, U.S., determined the mass of the 

 planet from observations of the satellite made by the late Mr. Bond, 

 Director of the Cambridge Observatory, and found it to amount to ^fato 

 in terms of the same unit. Adopting this value of the mass, Professor 

 Peirce calculated the perturbations produced by the plunct in the 

 motion of Uranus, and he obtained results which on the whole repre- 

 sent very satisfactorily the irregularities in the motion of the- latter 

 planet which so much perplexed astronomers previously to the dis- 

 covery of Neptune. It will be seen that the mass of NVp 1 

 deduced from the observations of the satellite either by M. otto 

 Struve or Mr. Bond, in considerably less than the value of the same 

 element assigned by Mr. Adams or M. Le Verrier. It is to be borne 

 in mind, however, that, on the other hand, the researches of both 

 these geometers make the distance of the planet from the sun greater 

 than the true distance. A compensation is thus effected, so that the 

 imimmty of the disturbing force presents a satisfactory agreement in all 

 three easel.' How nearly the airtrlioa of the disturbing force agrees 

 in so far as regards the real and the theoretical planets, has been shown 

 by the table just given. 



M. Kowalnki has recently published tables of Neptune, which are 



I in the ' Nautical Almanac' for computing the ephemeris of the 

 planet. Mr. Adams's researches on the theory of Uranus are to be 

 found in the Supplement to the Nautical Almanac for 1851 ; those of 

 M. Le Verrier on the same subject are published in the ' Connaissance 

 des Temps 'for 1849. 



NKnrxrs. [POMIDOS.I 



NKUK1HS (Ni),niloti>, nymphs of the sea, or rather of the Mediter- 

 ranean, in contradistinction to the Naiades, who were the nymphs of 

 fresh waters, and to the Ooeanides, who were nymphs of the great 

 ocean. The Nereids were the daughters of Kerens and Doris. Nereus 

 was the eldest son nf Pontus and the Karth (Hesiod, ' Theog.,' 233) ; 

 and Doris was one of the daughters of Oceanus. The Nereids are 

 said by most ancient writers to have been fifty in number, but I'm- 

 makes them a hundred (iii. 5, 83). The most celebrated of 

 them were Amphitrite, the wife of Poseidon ; Thetis, the mother of 

 Achilles ; Oalatea, Doto, 4e. (Homer, ' Iliad, xviii., 39-50, &c.) 



The worship of the Nereids wu generally connected, as might be 

 supposed, with that of Poseidon. Thus they were worshipped in 

 Corinth, when Poseidon wu held in especial honour, and in other parU 

 ece. They were the patrons of the Argonauts, and seafaring 

 people generally. (Paus., U. 1, | 7, 8 ; compare iii 20, 8 5 ; v. 19, * 2.) 

 Th Nereids are frequently represented on relievi, gems, tc. Tin y 

 are usually represented as beautiful nymphs [NYMPHS], mostly half 



draped, but sometimes unclothed. They are often figured sporting 

 with Tritons; sometimes riding on sea-panthers, griffins, the hippo- 

 campus, and other sea monsters. They are also seen u they 

 described by later writers, as beings with green hair, and wi: 

 lower part of their body like that of a fish (Pliu., ' Hi-t. Nat.' ix. 4.) ; 

 unless those on Greek gems are rather to be regarded u female Triton*. 



Bioo. Div.J 

 . in.l LACK. [Wr.AV; 



NKI'li M.i.l \. a word of modern origin (derived from trnfor, a 

 " nerve," and 0X701, " pain " ), first employed by Chaussier to designate 

 a certain class of diseases of which the characteristic symptom is a 

 most acute pain following the course of a nerve in one or more of its 

 ramifications, subject to paroxysms and intermissions, in most canes 

 unattended by either heat, redness, or swelling, and often without any 

 apparent lesion at all 



Although from the nature and causes of the affection we have every 

 reason to believe that neuralgia must have existed in all ages, still 

 (historically speaking) it may be called a modern disease, u the first 

 ik-scription of it that we possess is that published by Andre 1 , 

 a surgeon of Versailles, in 17f><>, in his ' Observ. Prat. BUT les Maladies 

 ile I I ti-thre.' He, however, hail only met with one species, namely, 

 vhich he called " tic douloureux," * a name win. li, 

 in popular language, it still retains; b. i time the same 



disease (subject only to certain local modiii--.it i..n.-i has been observed 

 in various other parts of the body, and it is probable 

 sensationary nerve is liable to the same morbid condition. Chnussier 

 has enumerated nine species (of which the three first 

 varieties of the neuralgia faciei), namely: 1. Ne<tral;fia frunlnlit, 

 which is seated in the frontal division of the first or ophthalmic I 

 of the fifth pair of cerebral nerves. The pain begins at the supra- 

 orbital foramen, and extends to the forehead, the upper eyelid, the 

 eyebrow, the caruncula lachrymalis, the inner canthus of the eye, and 

 sometimes to the whole of that side of the face. 2. Neuralgia tub- 

 orbitalu, which occupies the superior maxillary nerve, or second 

 division of the fifth pair. The iin begins at the infra-orbital foi 

 and extends to the cheek, the upper lip, the ate nasi, the low. 

 lid, and the teeth of the up]>er jaw. 8. Neuralgia nuurillarig, which 

 is seated in the inferior maxillary nerve, or third division of the fifth pair. 

 The pain commences at the mental foramen, and either extends to the 

 chin and lip, or else to the teeth of the lower jaw, the tongue, ami the 

 temple. 4. A'curafyiu ll'nt-miitnlii, which occupies the ilio-scrotal 

 nerve, or external division of the musculo-cutaneous branches given 

 off by the lumbar plexus, and derived from the first lumbar i 

 The pain commences at the crista ilii, follows the spermatic cor.l. and 

 extends to the scrotum and tli alyia ftmn, 



which is seated in the great sciatic nerve. The pain begins over the 

 sacrum, or about the great trochauter, follows the course of tin 

 down the posterior part of the thigh to the popliteal space, and thence 

 extends along the penmenl nerve, or external division of the great 

 sciatic, to the outside of the foot. 6. X> .vu/./m iliialit, 



whii-h occupies the crural nerve, given off by the lumbar plexus, and 

 derived from the second, third, and fourth lumbar nerves. The pain 

 commences at the crural arch, extends along the anterior and internal 

 pint of the thigh, and sometimes follows the course of the ; 

 s-iphcnom nerve, one of the tierp-teatcd branches of the crural, to the 

 inner ankle and the dorsiun of the foot. 7. .Vt/'niA,- uhich 



is seated in the external and internal plantar branches of the p< 

 tibial nerve, or intern. d divi.-ion of the great sciatic, 

 at the heel, shoots across the sole of the foot, 

 up the calf of the leg towards the knee. 8. .V 



which occupies the ulnar nerve, given oil' by the brae.hial plexus, and 

 derived from the fifth, sixth, seventh, and eighth cervical nerves. The 

 pain sometimes commences at the upper part of the arm, and follows 

 the course el :d> .n>,' the lunar border of the fore-arm to Ha 



termination in the inside of the middle, the iin^. and the 

 sometimes only part of the nerve is affected, and the pain is con I 

 the humerus, or commences at the elbow. 9. Anoma/rs : 



douleurs ordinairement chroniques, dont le siege vatic h I'itiiini." 

 i of these have been piirt.icul.irly described, and constitute so 

 many additional distinct species : 1. Olalyia (described I 

 v. hi ii i wateil in the corda tyinpani, a portion of the \ 

 or post. h of Meckel's gan-lin: and which is characterised 



by an acute pain following the course of this nerve,. . 



occurrence : M. Uosquillon has observed two cases 

 after opening th- external jugular vein, in consequence of wounding 

 the superficial branches of the cervical plexus formed by 

 branches of the second, third, and fourth cervical nerves ; and M. Jolly 



* The meaning of the term Tir Douloureux appear* to be rather doubtful. 

 In the ' Elctionnalrc do Trivoux,' the lint, a viciont 



tri'k that hornet have of biting the manger ; and secondly, " a sort of con- 

 vuKivc movement to which tome prrnons are ffuhject." Thcue twitching* not 

 being accompanied with p.iin, the epithet "douloureux "wan added to ditini<uish 

 thoM in neuralgia from errry other sort. Dr. Uood, however, connidcr* the 

 word tic to be "an onomalopy, or iwund cxpreimivc of the action it impart*." 

 The "Tic Douloureux" l e-alh-d " D-.l.ir crucian* l-'acici," by Futhi-rgill ; 

 "Trlimtu Maxillurii," and "Tium.u Dolurincun," by 8aurage ; " Proao- 

 pallia," by Swcdiaur; " Neuralgia l-'acici," by Good ; " AuUUgiu Dolorosa," by 

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