Page:Cyclopaedia, Chambers - Volume 2.djvu/727

 SIG

celebrated Sieges of Antiquity, are thofe of Troy, Tyre, Alexandria, Nltmantitm,lkc. Thofe of the Moderns are that of OJlend, Candid, Graves, ckc. The Word is trench, and dignifies, literally, Seat*

SIERRA, a..Spamfi Term fignifying Mountain ; applied to Mountains, and Mountainous Countries.

SIEVE, or Search, an Inftrument lerving to feparate the Fine from the Coarfe Parts of Powders, Liquors, !-§c. or to cleanfe the Pulfe from Dud, light Grains,' g)C.' 'Tis made of a Rim of Wood ; the Circle, or Space where- of is filled with a Tiffue of Silk, Tiffany, Hair, Line, Wire, or even rhin Slices of Wood. The Sieves which have large Holes, are uliially called Riddles; fuch is rhe Coai or Lime Sieve, Garden Sieve, &c. When Drugs, apt to evaporate, are to be paffed thro' the Sieve, 'tis ulual to have it covered with a Lid.

SIEUR, a Kind of Title of Honour, or Quality among the French ; chiefly ufed among the Lawyers, and in pub- lick Acts and other Writings of that Kind : As I plead for the Sieur Marquis, Jffc, The Title Sieur is properly given by a Superior to an Inferior, in his Letters, and other particular Writings : As, Tell the Sieur liich a one, that he proceed, ©c. In this Senl'e, Authors fometimes ufe it, by Way of Modelly, in fpeaking of themfelves. Thus, at the Heads of Books, we fee, TraduElion du Sieur d' Ab- lancourt, OEnvres du Sieur d' Uejpreaux, ckc,

Sieur, is alio a Term expreffing Seigneury or Lordfliip: As Ecuyer or Sieur of fuch a Place.

SIGHT, the Exercile, or Action of the Senfe of Seeing. See Seeing.

Our Sight, the nobleft and moff ufeful of all our Sen- fes, Father Mallebranch /hews, deceives us in abundance of Inttances; Kay, almolt in all : Particularly with Regard to the Magnitude, and Extent of Things ; their Figures, Motions, f£c. Our Eyes do not fhew us any Thing lefs than a Mite: Half a Mice is nothing, if we bel eve their Report. A Mite is only a Mathematical Point, with Regard thereto j and we cannot divide it without annihilating it. In effect, our Sight does nor reprefent Extenfion, fuch as it is in it felf ; but only the Relation and Proportion it has to our Body. Hence, as Half a Mite has no Relation to our Bodies, and that it cannot either preferve or delfrr y, our Sight hides it intirely. Were our Eyes made like Microf- copes, or were we our felvts as fmaU as Mites, we mould judge very differently of the Magnitude of Bodies. It may be added, That our own Eyes are really no other rhan a kind of natural Spectacles ; that their Humours do the lame Of- fice as the Lens's in Spectacles ; and that, according ro the Figure of the Cryflallin, and its Diftance from the Retina, Objects are fecn very differently ; inlomuch, as we are not fure. that there are any Two Perlbns in the World, who tee them equally big. 'Tis even very rare, that rhe fame Per- fon lees the fame Object equally big with both Eyes; as both Eyes are very ftldom perfectly alike: on rhe contrary, we generally fee Things bigger with the left than the right Eye ; Of which we have fome very good Obfervations in the Journal of the Learned at Rome, for the Year 1669. See Vision.

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SIG

Shcrt-SiGHT, Second S 'Point ifS

IT, •% f Ml

ht, \ See ) Se

llGHT, i lVi

Myopia, cond Sight, ew.

1

I

Sights, in Mathematicks, are Two thin Pieces of Brafs railed perpendicularly on the Two Extremes of an Alidade or Index of a Theodolire, Circumferentor, or other like In- ftrument: Each whereof has an Aperture or Slit up the Mid- dle, thro' which the ufual Rays pafs to the Eye, and di- ftant Objects are feen. Their Ufe is for the juft Direction of the Index to the Line of the Object. See Telescope, Circumferentor, Alidade, £&.

Tlain. Sight, ^ <, CSights.

TelefeopicSiGHTs, 5 cTelescopi

c Sights.

Mr. Flamflead and Hr.Hook, abfolutely explode the Ufe of 'Plain Sights in Agronomical Obfervations. The Errors in Tycho's Latitudes of the Stars, Mr. Flamftead afcribes wholly to his ufing 'Plain Sights; and fufpects, that Hevelius ufing the fame Kind of Sights, will fall into the like Errors. Hevelius, on the contrary, in a Paper in the 'Philofophical WrmfaSions, vindicates the Ufe of ' 'Plain Sights, and prefers them to Telescopic ones. The main Objection he makes to the latter, is, That no Obfervation can be fafely taken with them, without firft examining and rectifying them : In which Examination, many and grofs Mi Hakes are liable to be com- mitted. To which he adds, That in Sextants, Octants, Azimuth Quadrants, £S?r. he does not fee haw fuch Exami- nation can be made, at all times, without much Lofs of Time.

SIGILLARIA. a folcmn Feaft held among the ancient Remans ; thus called from a Cuftom which obtained therein,

of fendmg little Prefents from one to another ; conlifting of Seals httie Gravmgs, Sculptures, s£ c. The Mfliria fol- lowed immediate^- after the Saturnalia, and held Four Days; which, with the Three Days of the Saturnalia, made a So! lemnity of Seven Days. The Inftitution of the Sigillm* is referred, by fome, to Hercules; who, upon his Return from Spain, .after k, l,ng Geryon, led his Flocks into Italy where T ™? ,lc % B': ,d « e ov " the ?»**, at a Place, where was fmce- the^oas Svdicms mReme. Others alcribe it to theTclrtian ; who conceiving, that by the Words Head and Oj the Ora^ cle did not require livmg Men to be facrificed to it, but Sta- tues, or Figures of Men by the Firft, and Lights by the Second ; began to offer Torches ro Saturn, and human Fi- gures ro 'Pluto.

SIG1LLATA TERRA, a Kind of Earth or Clay, dug in the Iile of I.enwos, thence alio called Lemuiau Eatth 5 of confiderable Ufe in Painting, and Medicine. 'Tis of dif- ferent Colours, but molt commonly Red ; heavy, fofr, and friable; held very allringent, and, as fuch, ufed in Haimorrhages ; as alio againlt the Plague and Poifbns. 'Pliny attributes feveral other Virtues, which Experience does not juftify; nor is it in that Efteem it anciently was ; yet is ftill an Ingredient in Treacle. 'Twas anciently found in a Mountain, in the Neighbourhood of the City Hephif- flia ; where 'Diana's Prieffs went at certain Times, with. great Ceremony, to dig it up. After a little Preparation they made it up into Troches, and feal'd them with Diana'* Seal ; whence the Appellation of Slgillata, S al' !. 'Tis now brought from Conpntinople in little Cakes orbicular, on one Side flat, on the other fealed. See Terra.

SIGILLUM, a Seal or Signet. See Seal and Signet.

SIGN, a ienfibie Mark or Character, denoting fome- thing abient, or invifible. See Character and Mark. Antientiy, the Monks, in all Religious Houles, were not al- lowed to fpeak ; nor to expreis their Minds otherwile than- by Signs, which they learned in their Novitiate. C. Rhodi- gims and Porta have wrote of the ancient Signs and Cy- phers ufed in Speaking and Writing.

Sign, in Medicine, lome Appearance in the Body, diflin- guifhable by the Senfes : Whence, byjull Reafomng, is in- ferred the Prefence. Nature, State, Event, of Health, a Difeale, or Death. Thofe which denote the prefenc Condition of a Body, whether fick or well, dying or the like, are called THAgmflic Signs. See Diagnostic Thofe which toretel me future State thereof, are called 'PngncfiiC Signs. See Prognostic. That Sign which is proper to the Difeale, and mfeparable from ir as anting from the Natute thereof, is called a 'Patbrgcnomic Sigir. See Pa- thogf.nomio As all thefe are Effects produced by the Came of the Difeale, the Difeafe it felf, and us Svmptoms; they uliially nore the prefenr Condition 0; the Mj ; rer which, fitif produced toe Difeafe, and even of mat p oduced by the Difeafe; On which Fooring, the Signs are ail reducible to thefe Three dalle-, viz-. SgaS of the Crirdrry and Digc- flion of the Difeale; of its Event, whether in Health, a Dif- eafe or Death ; and of itsSecretion and Excretion : Which laft Signs ire called Critical ones. See Crudity, Digestion, (Sc. each under its proper Article. See aifb Health and Disease.

Sign, in Aftronomy, a Twelfth Part of the Ecliptic, or Zodiac ; or a Porrion containing Thirty Degrees thereof. The Zodiac was divided by the Antients into Twelve Segments, called Signs ; commencing from rhe Point of Interfedion of the Ecliptic and Equinoaial: Which Signs they denominated from the Twelve Conffellations, which, in Hipparcbus's Time, poffefled thofe Segments; But the Conffellations have fince fo changed their Places, by the Prxccfion of the Equinox, that Aries is now got out of the Sign called Aries, into Taunts, Taurus into Gemini, ike.

The Names of the Twelve Signs, and their Order, are as follow ; Aries, Taurus, Gemini-, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricornus, Aquarius, 'Pijces : Each of which, with the Stars thereof, fee under its proper Article.

The Signs are dillinguimed with Regard to the Sealbn of the Year when the Sun is in them, into Vernal, Eflival, Autumnal, and Brumal. The Vernal, or Spring-Signs, are Aries, Taurus, Gemini : The Eflival, or Summer-Signs, Cancer, Leo, and Virgo .- The Autumnal-Signs, Libra, Scor- pio, and Sagittarius ; and the Brumal, or Winter-Signs, Ca- pricornus, Aquarius, Tifces. The Vernal and Summer Signs, are alfo called Northern Signs, and the Autumnal and Bru- mal Signs, Southern Signs.

For the Motion of the Signs. See Precession of the Equinox.

Sign Manual, the fetting one's Hand and Seal to a Writing. See Signature. Among the Saxons, beforerhe Invention of Seals, a 4- was a common Sign or Signum, prefixed to the Names of mod fubferibing Wirneffes in Charters and other Deeds, as -\- Signum Roberti Epifcop. Land. &c.

SIGNAL, a certain Sign agreed upon for the conveying of Intelligence whither the Voice cannot reach. Signals are given for the beginning of a Battle, or an Attack : Some- times