570 



OBSIDIAN 



OBSTKTKICS 



llahylnnian* and Kgvptiana, Of modern olmerva- 

 toii.'- i lint HI Camel dates from 1561, Tycho Itrahc's 

 at L'ranienburg from 1576 : tliut of Greenwich (t{.v.) 

 was founded in 1675. The oldest in tin- lulled 

 States is the Hopkins Observatory, Williams 

 College, erected in 183 ; now there are upwards of 

 sixty, of which those of Washington and Harvard, 

 ami the Lick Observatory (<|.v.)are the chief. The 

 highest in the world is that on Mont Blanc, at a 

 height of 14,470 feet. 



Obsidian, a natural glass the vitreous con- 

 dition of an acid lava. It is hard and brittle, with 

 remarkably vitreous lustre, and perfectly con- 

 clmidal fracture, the edges of the fractures very 

 sharp and cutting like glass. It varies from semi- 

 transparency to translucency only on the edges. 

 It is often 'black or MTV dark gray; sometimes 

 green, red, brown, striped, or spotted ; and some- 

 times chatoyant or tinint urine. Some obsidians 

 are rendered porphyritic with microscopic crystals 

 of sanidine ; others are often highly vesicular and 

 plentifully charged with spherulites usually arranged 

 in the line of lava-flow. The rock is usually rich 

 in crystallites and microlites (the 'beginnings of 

 crystallisation'), which are frequently arranged in 

 parallel or undulating lines = ' fluxion-structure. ' 

 Steam- or vapour-pores of minute size occur 

 abundantly in some obsidians. Obsidian is thus a 

 kind of lava. It is capable of l>eing polished, but 

 is apt to break in the process. It is made into 

 boxes, buttons, ear-drops, and other ornamental 

 articles ; and liefore the uses of the metals were 

 well known it was employed, in different parts of 

 the world, for making arrow and spear beads, 

 knives, &c. It is found in Iceland, the Lipari 

 Isles, Vesuvius, Sardinia, Hungary, Spain, Tener- 

 iffe, Mexico, South America, Madagascar, Silieria, 

 iVc. Black obsidian was used by the ancients for 

 making mirrors, and for this purpose was brought 

 to Rome from Ethiopia. It was used for the same 

 purpose in Peru and Mexico. Mirrors of black 

 obsidian are indeed still employed by artists. 

 Chatoyant or avanturine obsidian is very beautiful 

 when cut and polished, and ornaments made of it 

 are sold at a comparatively high price. 



Obstetrics (I^at. obstetrix, 'a midwife,' from 

 obsto, ' I stand before,' thus literally ' a woman who 

 stands before or beside another '), called also MID- 

 WIFERY (A.S. mid, 'together with,' and wif, 'a 

 woman'). As a branch of medical science and 

 practice obstetrics is concerned with the study and 

 care of women during the processes of pregnancy, 

 parturition, and the puerperium, or lying-in. As 

 a department of medical study it embraces the 

 anatomy and physiology of the female organs of 

 generation, the phenomena of conception and preg- 

 nancy, of labour, normal and abnormal, and of the 

 pner|wrium and the return of the organs to their 

 non-pregnant condition. Strictly speaking, these 

 processes are normal and physiological, and in per- 

 fectly natural conditions require little or no skilled 

 help or assistance. Hut, while theoretically this 

 may be so, it is still the case that these processes 

 each produce an effect on the female organism 

 which results in great modifications of the ordinary 

 vital functions, so that the condition is one of con- 

 tinued physiological ten-ion, which at any moment 

 may iiass into a pathological or almormal condition 

 in which skillet! assistance is of the utmost im- 

 portance. There can further be no doubt that 

 many influences at work in states of civilisation 

 tend greatly to increase the dangers of the repro- 

 ductive process, so that the members of highly 

 civilised communities are peculiarly liable to dis- 

 aster; bnt at the same time the rudest savages are by 

 no means free from these risks, and the care which 

 most of them take of their women during pregnancy 



and parturition amply proves how conscious they 

 are of this fact (but see I'm VAI>K). Tin- dm 

 with which llie reproductive process is iiKsociaicd 

 may be in some measure realised when it is nn.l.-i 

 stood that during pregnancy women an- liable to le 

 affected by many of the ordinary disease- in an 

 aggravated form, which may give rise, to premature 

 expulsion of the ovum aliortion a process in it-elf 

 attended by grave dangers; thai during iiartuii- 

 tion the child may present by some part ol' tin- body 

 other than the head, causing increased difficulty, 

 often impossibility of spontaneous delivery; that 

 there may l>e some di-pro]H>rtion between the size 

 of the child's head and the pelvis, .in.- to disease or 

 deformity; that from disease or exhaustion the 

 uterus may be incapable of expelling its contents : 

 that after the birth of the child the natural pro- 

 cesses for checking hemorrhage from the site of 

 the placenta tuny be at fault, or again the retention 

 of a blood -clot or fragments of placenta may expose 

 the patient to the risks of scptincima or blood- 

 poisoning. These are but a tithe of the dangers 

 which surround the reproductive process, but they 

 give an ample explanation of the existence of a 

 science and art of obstetrics bv which these ami 

 similar dangers may l>e obviated. AVith regard to 

 parturition itself it may be noted that the great 

 majority of labours (95 per cent.) are natural i.e. 

 the head presents, and they are spontaneously 

 accomplished within twenty-four hours. Hut in 

 civilised countries, and under the l>est practice, it 

 is estimated that one in 120 women dies within a 

 fortnight after labour. It would l>e out of place 

 in a work of this kind to enter into the details of 

 this science, but a sketch of the history of iu 

 origin and development may be of interest. 



I'ntil about the lieginning of the Kith century 

 the practice of obstetrics \vas mainly empirical. It 

 was founded on experience and superstition, and 

 was in great measure destitute of an anatomical or 

 physiological foundation. Such practice is seen in 

 the present day among uncivilised races, and we 

 find procedures described as employed by the 

 Egyptians, Jews, Greeks, and Komans in vogue 

 among the North American Indians and negroes at 

 the present time. During the empirical period we 

 find, as we might expect, that the ordinary practice 

 was wholly in the hands of women. At first female 

 friends and neighbours would perform what kindly 

 offices they could, but soon a distinct class of mid- 

 wives arose, whose ex|>eriences or special aptitude 

 fitted them for the duty. All ordinary labours 

 were attended by them, and they did not yield up 

 a difficult cnse to the surgeon or physician until 

 they had exhausted a code of practice partly reason- 

 able as founded on experience, partly superstitious, 

 but often very elaborate. AA'hen these resources 

 failed, the aid of the male practitioner, who com- 

 bined the offices of priest and physician, was usually 

 invoked. At first the aid yielded by these was 

 largely based on superstition, consisting in charms, 

 incantations, and invocation of special deities. 

 Eilithyia among the Greeks and Lucina among the 

 Romans were the chief deities presiding over child- 

 birth, though among the Romans particularly a 

 numlier of minor deities were regarded as specially 

 available for special complication*. With the 

 growth of medical knowledge the purely religi- 

 ous office of the priest liccnme detached from 

 that of the physician, and anionp the Egyptians 

 in quite early times the physician became a 

 separate functionary and rendered much more 

 practical aid. The ignorance of the anatomy of 

 the organs involved greatly limited their practice, 

 and cases of difficult or delayed labour were usually 

 treated by Cswarean section, or later by some form 

 of embryotomy. See C^ESAREAN OPERATION. 



The writings of Hippocrates (400 B.C.) contain 



