INTERJECTIONS. 



INTERMENT. 



933 



planes of the mirrors is much removed from the edges in contact. A 

 little jutting is easily got rid of by gently squeezing the wax. Now 

 reflect the sun's light into a darkened room, passing it through a lens 

 of short focus (suppose J inch) placed in the window. A second lens 

 may be added at a little distance in case the focal length of the first 

 lens be not short enough to give a sufficiently small image of the sun. 

 Let the light diverging from the image of the sun be reflected, at the 

 distance of a few feet, from the mirrors, at any convenient angle, and at 

 the distance of a few feet from the mirrors examine with a lens the 

 doubly bright portion of the field where the two reflected streams mix. 

 This will be seen traversed by a series of fine bands, called fringes of 

 interference, alternately bright and dark near the middle fringe, and 

 coloured on receding from the middle. They are readily distinguished 

 from the vague fringes seen at the edges of the doubly illuminated 

 portion of the field by the blackness of the minima near the centre of 

 the system, and also by their position, as they are always perpendicular 

 to the line joining the two virtual images formed by the light reflected 



burning on a funeral pile. The practice of burying is probably the 

 oldest mode, and with most nations has been the ordinary mode of 

 sepulture ; but the custom of burning the body, and afterwards col- 

 lecting the ashes and depositing them in a tomb or urn, became very 

 general among the Greeks and Romans. Among the Greek nations, 

 however, both the burning of the dead and the interment of dead 

 bodies in the earth were practised. The Romans in the earlier periods 

 of their history certainly buried their dead. It is recorded that Sulla 

 was the first member of the Cornelia gens who was burnt. The 

 Egyptians do not seem to have ever adopted the practice of burning 

 the dead ; and though, as we have observed, burning became common 

 among the Greeks and Romans, it seems that interment was always 

 practised by the lower orders among the Romans. At Rome, bodies 

 were sometimes buried in pits (puticuli), or thrown to decay in certain 

 unfrequented places. (Varro, 'De Ling. Lat.' v. 25; Horace, 1, Sat. v. 

 8, &c.) Tacitus (xvi. 6) speaks of the embalming and interment of 

 Poppaea, the wife of Nero, as a deviation from the general practice. 



from the two mirrors respectively, and therefore run obliquely across i The practice of burning the dead appears to have gradually gone into 

 the doubly illuminated portion of the field when the mirrors are I* disuse und 



adjusted so that the line of intersection of their planes is oblique to 

 the edges in contact. Instead of the mirrors Fresnel used also a flat 

 prism with a very obtuse angle, the fringes in this case being formed 

 by the transmitted light. 



The explanation of these fringes follows at once from the principle 

 of interference. The length of the path of either reflected stream is 

 the same as if the light came from the corresponding virtual image of 

 the luminous point. We may suppose therefore that we have two 

 perfectly similar series of waves starting simultaneously from the two 

 virtual images respectively (which we may call I, i'), and mixing 

 within the wedge-shaped portion of space where the reflected streams 

 cross. Any point of a plane bisecting 1 i' at right angles will be equi- 

 distant from i and i', and therefore at any such point the two streams 

 will conspire, and that for light of all colours. For any particular 

 kind of light the two streams will again conspire at a point whose 

 distances from I, i' differ by A, 2A, 3A, &c., X being the wave-length for 

 that kind of light. The locus of such a point will evidently be a 

 hyperboloid generated by the revolution round 1 1' of a hyperbola having 

 I, i' for its foci, and A, 2A, 3A, &c., for its transverse axis. Along the 

 intermediate hyperboloids whose transverse axes are JA, JA, &c., the 

 two streams will be in perfect opposition, and will completely neutralise 

 each other. On account of the excessive smallness of A (which varies 

 from about the one forty-thousandth to the one sixty-thousandth part 

 of an inch in passing from the red to the violet), a section of these 

 hyperboloids by a small plane at the focal distance of the eye-lens will 

 not sensibly differ from a series of equidistant lines parallel to the 

 plane first mentioned. Hence any one kind of light forms a system 

 of parallel bands alternately bright and dark, but the scale of the 

 system decreases from the red to the violet, so that beyond a moderate 

 distance from the central bright fringe, which is common to all the 

 colours, the fringes obliterate each other by overlapping. 



We have seen that the phenomena of interference are by no means 

 confined to light. The beatt for instance heard when two musical 

 notes are very nearly but not exactly in unison, are a phenomenon of 

 interference of sound. For the description of a very elegant experi- 

 ment rendering the interference of sound a matter of ocular inspec- 

 tion, the reader is referred to a paper by Mr. Hopkins, published in 

 the 5th volume of the ' Transactions of the Cambridge Philosophical 

 8.i,-ty,' p. 257. 



INTERJECTIONS have been defined to be " words used to express 

 some passion or emotion of the mind," as exclamations of joy, grief, 

 astonishment, &c. Interjections however can hardly be considered as 

 a distinct part of speech, but are more properly natural sounds com- 

 mon to all men when laughing, in pain, Ac. Many words, such as 

 malum, made, profecto, Ac., in Latin, and adieu, welcome, &c., in Eng- 

 lish, which have been considered as interjections by grammarians, 

 ought to be regarded as verbs, substantives, adjectives, or adverbs. 



INTERLOCUTORY (inter, between, and loquor, to speak) a term 

 applied to those judgments, decrees, and orders of courts of law and 

 equity which are made in the progress of a suit before final judgment. 

 Thus, orders for the production of papers, for taking an account of the 



out of which the dispute arises, are interlocutory orders or 

 decrees. Those judgments which, though they establish the right of 

 the plaintiff, leave t^e amount of damages to be ascertained by a jury, 

 arc generally, but incorrectly, termed interlocutory judgments. 



INTERLUDE, a brief piece of church music for the organ, seldom 

 exceeding a few bars, generally produced ex tempore, and played after 

 each stanza, except the last, of the metrical psalm. This, being merely 

 for the purpose of giving breathing time to the singers, should always 

 be short and grave, and in keeping with the psalm tune. 



Interlude is also the name for a stage-play, among the earliest of the 

 Inductions of English dramatic literature. It belonged originally to 

 the claw of " moralities," and John Heywood, in the time of Henry VIII., 

 'i first to free it from allegorical materials. In modern times 

 the name has been still further extended, and is often applied to a 

 ohort dramatic piece performed between two others. 



INTERMENT, the burial of a dead body in the earth. The manner 

 of disposing of the bodies of the dead has varied in different nations ; 

 but the most general modes have been interment in the earth and 



ARTS AKD SCI. Dl\. VOL. IV. 



nder the Empire : and probably it was never practised by the 

 Christians. 



A constitution of the Emperor Justinian (A.D. 537) regulated the 

 expense of funerals in Constantinople. The constitution refers to 

 prior legislation of Constantino and Anastasius. The object of the 

 I regulation is well expressed in the following words : It was to " secure 

 men against the double calamity of losing their friends, and at the 

 same time incurring heavy pecuniary liabilities on their account." 

 Provision was made for securing interment to each person free of cost, 

 and for protecting the surviving friends from the extortion of those 

 who buried the dead. Funds were appropriated for the purpose of 

 interment, which was conducted by persons appointed for the purpose, 

 and with decency, but at little cost. All persons were to be buried 

 alike, with some small allowance in favour of those who wished for a 

 little more display at their own cost ; but even this additional expense 

 was limited ; and it is said, " thus there will be nothing undetermined ; 

 but both those who wish to have funerals on a moderate scale will 

 enjoy the advantages of our rule, and those who wish for more liberal 

 arrangements will not be mulcted heavily, and will be enabled to show 

 their liberality at moderate cost." The whole constitution is very 

 curious ; but a full explanation of it would require some labour. The 

 objects of it have, however, been sufficiently stated here. The means 

 by which they were accomplished would not be suitable to this country. 

 (Novell, 1 59.) 



At Bombay, says Niebuhr (' Reisebeschreibung,' &c. ii. 50), " the 

 Parsees have a peculiar manner of interring their dead. They do not 

 choose to rot in the earth like the Jews, Christians, and Mohammedans, 

 nor be burnt like the Indians ; but they let their dead be digested in 

 the stomachs of birds of prey. They have at Bombay a round tower 

 on a mountain at some distance from the city, which is covered on the 

 top with planks. Here they place their dead, and after the birds of 

 prey have eaten the flesh, they collect the bones below in the tower, 

 and the bones of the men and women in separate vessels." Herodotus 

 (i. 140) says of the ancient Magi, that they never interred their dead till 

 they were torn by birds or dogs. In Herbert's ' Travels ' (ed. 1638, 

 p. 5 J), there is a representation of one of these Parsee towers. Some 

 nations have eaten the aged, and also killed and eaten those who were 

 attacked by disease, and thus anticipated the trouble of interment. 

 This revolting practice is established on sufficient evidence. (Herodotus, 

 i. 216, iii. 99; 'London Geog. Journal,' ii. 199; BATTAS, in GEOO. 

 Div.) Dr. Leyden states that the Battas frequently eat their aged 

 or infirm relatives, as an act of pious duty. The Battas are not a 

 ferocious, but a quiet and timid people. Niebuhr says in a note to the 

 extract given just above, " At Constantinople I heard, that in tho 

 southern part of Russia there in a people who think that they can 

 show to their dead friends and relations no greater honour than to eat 

 them. So different are the opinions of mankind." 



These are, however, singular exceptions to the general practices of 

 all nations. Among the Europeans, and those descendants of Euro- 

 peans who have settled in parts beyond Europe, the interment of the 

 dead in the earth is the universal practice. It was proposed, indeed, to 

 revive the practice of burning during the French revolution, but the 

 proposal was not adopted. It has also been the practice of all nations 

 called civilised, and perhaps of most nations called barbarous, to treat 

 the dead with decency, and to accompany the funeral ceremony with 

 religious rites. 



The places set apart for the burial of the dead are generally called 

 cemeteries, which is a Greek term signifying " a place of rest or sleep," 

 and was applied to common places of interment by the early Christians. 

 Among the Greeks, cemeteries were perhaps always without the cities. 

 Among the Romans, the tombs were generally placed by the sides of 

 the public roads. It was an enactment of the Twelve Tables that a 

 dead body was not to be buried or burnt within the city (Dircksen, 

 ' Zwolf-Tafel Frngmente,' p. 657). The prohibition against burning 

 in the city is supposed by Cicero to have been made to prevent risk 

 from fire : the reason for interment not being allowed within the city 

 is not stated. A regulation of the Twelve Tables appears to havo 

 limited expenses at funerals (Dircknen, p. 665) ; and a law to the tamo 

 effect was passed in the time of the Dictator Sulla (Plutarch, ' Sulla,' 

 c. 35). 



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