Page:Encyclopædia Britannica, Ninth Edition, v. 8.djvu/181

Rh E M E E M E 171 himself up in London during the publication of his works, and carefully revised them sheet by sheet himself, so that they are singularly free from errata. In mechanics, he never advanced a proposition which he had not previously tested in practice, nor published an invention without first proving its effects by a model. Emerson was married, but had no family. His wife employed her leisure in spinning on a curious wheel, of which an accurate drawing is given in his Mechanics. His own favourite recreation was fishing. He was skilled in the science of music, the theory of sounds, and the ancient and modern scales; but he never attained any excellence as a performer. The following is a list of Emerson s works : The Doctrine of fluxions, 1748, 8vo ; The Projection of the Sphere, orthographic, stercograpldc, and gnomical, 1/49, 8vo ; The Elements of Trigono- inelrii, 1749, 8vo ; The Principles of Mechanics, 17 54, 8vo ; A Treatise of Navigation, 1755, 12mo ; A Treatise of Algebra, in two books, 1765, 8vo ; The Arithmetic of Infinites, and the Differential Method, illustrated by Examples, 1767, 8vo ; Mechanics, or the Doctrine of Motion, 1769, 8vo ; The Elements of Optics, in four looks, 1768, 8vo ; A System of Astronomy, 1769, 8vo ; The Laivs of Centripetal and Centrifugal Force, 1769, 8vo ; The Mathematical Principles of Geography, 1770, 8vo ; Tracts, 1770, 8vo ; Cyclomathcsis, or an easy Introduction to the several branches of the Mathematics, 1770, in ten vols. 8vo ; A short Comment on Sir Isaac Newton s Prin- cipia ; to which is added, A Defence of Sir Isaac against the objec tions that have been made to several parts of his works, 1770, 8vo ; A Miscellaneous Treatise containing several Mathematical Subjects, 1776, 8vo. EMERY (Greek, O-/AV/DIS ; Spanish, esmeril), an impure variety of the mineral corundum, bluish-grey to brownish in colour, dimly translucent, and granular and rough in fracture, and having a hardness of 9, and specific gravity varying between 37 and 4 3, Much of the emery of com merce is artificially coloured of a rich reddish brown. Analyses of emery show a percentage composition of from about 60 to 80 per cent, of alumina, and 8 to 33 per cent of ferric oxide, with small quantities of lime, silica, and water. It occurs in amorphous masses in schists, gneiss, granular limestone, and other crystalline rocks, and in rolled and detached pieces and in granules in soils, The principal European source of emery is the island of Naxos, which in 1872 exported to England 1270 tons, to Hamburg 250 tons, and to Rotterdam 300 tons of the mineral. It occurs also near Smyrna, and in Sweden, Saxony, Spain, Green land, Massachusetts, and other localities. Emery is used as a polishing material for plate-glass, crystal, lapidaries work, and metals, and in cutting granite and marble. It is pre pared for use by breaking with hammers, crushing with steel stamps, and sifting. Combined with leather by the American &quot; tanite &quot; process, or treated after Ransome s method for the manufacture of artificial stone (see COX- CRETE, vol, vi., p. 243), emery powder is formed into grinding wheels, hones, and similar instruments. Emery, more especially that used for emery-paper and emery-cloth, is commonly adulterated with garnet, zircon, iron-slag, and other substances harder than quartz sand. EMETICS, substances which are administered for the purpose of producing vomiting. They are usually regarded as of two varieties, viz., those which produce their effect in virtue of their absorption into the blood and consequent influence upon the nerve centres, and those which act topically on the mucous membrane of the stomach, giving rise to vomiting as the result of reflex action. The former class of emetics are slower in their operation and are attended with much greater depression of the system and antecedent nausea than the Litter, the action of which is prompt. The use of emetics in medicine is comparatively rare, although at one time they were often resorted to in the early stages of acute diseases, such as fevers and inflammations, with the object of cutting them short. Their power, however, to accomplish this is more than questionable. Among the purposes for which emetics are employed are the following to empty the etomach in certain cases of poisoning, such as by narcotics or where indigestible substances are giving rise to disturbance which calls for their removal, and to clear the air passages of obstructions, as in certain cases of bronchitis or croup, where the respiratory tubes become filled with morbid material which threatens death by asphyxia, and which cannot be dislodged by coughing, Eor both these pur poses the stimulating emetics are to be preferred, such as the sulphates of zinc and copper, or, where these are not available, mustard stirred into water. Again, emetics are employed in producing, short of their emetic action, a certain degree of nausea and consequent relaxation during the early stages of acute inflammation in strong persons, and for this purpose the more depressing emetics are resorted to, such as antimony, ipecacuanha, apomorphia, &c. The latter are likewise employed in obstetric prac tice with the view of producing relaxation in cases of protracted labour from uterine and muscular rigidity. Emetics ought always to be administered with caution, since the act of vomiting may be attended with danger where there exists any tendency to brain disease or in cases of disease of internal organs; or further, from the vomiting continuing longer than was intended, injury may be done to the mucous membrane of the stomach as well as serious shock inflicted on the system. EMEU, evidently from the Portuguese JEma,^ a name which has in turn been applied to each of the earlier-known forms of Ratite Birds, but has in all likelihood finally settled upon that which inhabits Australia, though, until less than a century ago, it was given by most authors to the bird now commonly called Cassowary this last word being a corrupted form of the Malayan Suwari (see Crawfurd, Gramm. and Diet. Malay Language, ii. pp. 178 and 25), apparently first printed as Casoaris by Bontius in 1C58 (Hist. nat. et med. Ind. Orient, p. 71). The Cassowaries (Casuariida j ) and Emeus (Dromceidce} as the latter name is now used have much structural resemblance, and form the Order Megistanes, 2 which is peculiar to the Australian Region. Professor Huxley has shewn (Proc. Zool. Soc. 18G7, pp. 422, 423) that they agree in differing from the other Hatitai in many important characters, into the details of which it is now impossible to enter ; but one of the most obvious of them is that each contour -feather appears to be double, its hyporrhachis, or aftershaft, being as long as the main shaft a feature noticed in the case of either form so soon as examples were brought to Europe. The external distinctions of the two families are, however, equally plain. The Cassowaries, when adult, bear a horny helmet on their head, they have some part of the neck bare, generally more or less ornamented with caruncles, and the claw of the inner toe is remarkably elongated. The Emeus have no helmet, their head is feathered, their neck has no caruncles, and their inner toes bear a claw of no singular character. The type of the Casuariidce is the species named by Linnaeus Struthio casuariits and by Latham Casuarius emeu. Vicillot subsequently called it C. c/aleattis, and his epithet 1 By Monies 0796) and Sousa (1830) the word is said to be from the Arabic Na Ama or Na tma, an Ostrich (Struthio camelus); but no additional evidence in support of the assertion is given by Dozy in 1869 (Glossaire dcs mots espagnols ct portitgnis dtrivtt de Paralx. Ed. 2, p. 2GO). According to Ge.sner in 1555 (lib. iii. p. 709), it was the Portuguese name of the Crane (Grus communis},^ and had been transferred with the qualifying addition of &quot;di Get&quot; (i.e., Ground- Crane) to the Ostrich. This statement is confirmed by Aldrovandus (lib. ix. cap. 2). Subsequently, but in what order can scarcely now be determined, the name was naturally enough used for the. Ostrich-like birds inhabiting the lands discovered by the Portuguese, both in the Old and in the New World. The last of these are now known as Rheas. and the preceding as Cassowaries. 8 Ann. and May. .Vat. Hist. ser. 4, xx. p. 500.