Page:Cyclopaedia, Chambers - Volume 2.djvu/823

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World) and the Immenfity thereof: Hence arifes a Syftem of Syftems. See Universe.

The planetary Sy/lem, here defcribed, is the moft ancient in the World. 'Twas the fifft that we know of, introduced into Greece and Italy by 'Pythagoras; whence, for many A«cs, it was call'd the 'Pythagorian Syftem. It was followed by "Piatt, Jrchimsdes, §£?£ but loft under the Reign of the Peripatetic 'Philosophy; till happily retrieved above 200 Years ago by Nic. Copernicus; whence its new Appellation, of Copemican Syftem. See Coper nic an.

For the Oeconmny of the Copernican Syllcm; fee the Scheme thereof, Tab. Attronomy, Fig. 44.

Tychonic System, in moftrefpecfs,coincideswith theCop'er- vican; except in this, that, fuppofing the Earth to be fix'd, its Orbit is omitted, and in lieu thereof, the Sun's Orbit is drawn round the Earth, and made to interfecl the Orbit of Mars; that Mars may be nearer the Earth than the Sun. But as there is not any Reafon, or Foundation in (Nature, for fiich a manifelt Shift; and as the Author was only led thereto, from a fupcrftitious Fcifuafion, that to fuppofe the Sun at Reft, and the Earth to move, is contrary ro Scripture; the tmcSyftem is not much prejudiced hereby. See Earth..

For the Order and Occmomy of the Tychonic Syftem; fee the Scheme in Tab. Aftronomy, Fig. 4J.

System, in Poetry, is a certain Hypothec's, from which rhe Post is never to recede; e.gr. Having made his Choice either in the Fables of the Heathens, or in Chriftianity; he muft always diftinguifh. between the Two; and never mix fuch different Ideas in the fame Poem. Thus, after invoking Apollo and the Mules, he muft bid adieu to the Language of Chriftianity, and ■not confound the two Syftems. The Fabulous Stile, indeed, is the Gaver and more Figurative; but a Pagan God makes but a miferable Figure in a Chriftian Poem. The Syftem of Poetry, Smhours obierves, is, itfelf, wholly Fabulous and Pagan.

System, in Mulic, a compound Interval; or an interval compofed, or conceived to be compofed, of feveral leffer 5 fuch is the Ocfave, $£c. See Interval.

The Word is borrowed from the Ancients, who call a fimple Interval, Diaftem, and a Compound one Syftem.

As there is not any Interval in the Nature of Things; fb we can conceive any given Interval, as compofed of, or equal to the Sum of feveral others. This Divilion of Inter- vals, therefore, only relates to Practice 5 fo that a Syftem is properly an Interval, which is actually divided in Practice, and where, along with the Extremes, we conceive always fome intermediate Terms. The Nature of a Syftem will be very plain, by conceiving it an Interval, whofe Terms arc in Practice, taken either in immediate Succeffion; or the Sound is made to rife and fall, from the one to the other, by touching fome intermediate Degrees; fo that the whole-is a Syftem or Com- pofition ofall the Intervals, between one Extreme andtheother. Syftems of the fame Magnitude, and confequently of the fame Degree of Concord and Difcord, may yet differ in refpect of their Composition; as containing and being actually divided into more or fewer Intervals : And when they are equal in that refpeel, the Parts may differ in Magnitude. Laftly, when they confift of the fame Parts, or leffer Intervals, they may differ as to the Order and Difpofition thereof between the two Ex- tremes.

There are feveral Diftinclions of Syftems; the moft re- markable is, into Continuous and Jnconcinnoits.

Continuous Syftems, are thofc confifting of fuch Parts, as are fit for Mufie, and thofc Parts, placed in fueh an Order between the Extremes, as that the Succeffion of Sounds, from one Ex- treme to the other, may have a good Effecl. See Con- cinnous.

inconcinnoiis Syftems, are thofe, where the fimple Intervals are Inconcinnolis, or ill difpofed betwixt the Extremes.

A Syftem, again, is either 'Particular or Univerfal. An tlniverfl Syftem, is that which contains all the particular Syftems belonging to Mulic 5 and makes what the Ancients call theDiagramma. and we the Scale of Muftc. See Scale.

The Ancients alfo diftinguifh Syftems 'into Perfetl and TmferfeU. The Difdiapafon, or double Octave, was reckon'd theperfeff Syftem, becaufe within its Extremes, are contained Examples of all the fimple and original Concords, and in all the Variety of Order wherein their concinnous Part ought to be taken *, which Variety conftitutes what they call the Species or Figures of Confonances.

All the Syftems, lefs than the 'Difdiapafon, were reckoned Jmfierfetl.

The double Oclave was alfo called the Syftema- Maximum, and Immutatum; becaufe they took it to be the greateft Ex- tent or Difference of Time that we could go inmaking Melody; though fome added a Fifth to it, for the greateft Syftem : But the Diapafbn, or limple Oclave, was reckon'd the moft petfeel, with refpect to the Agreement of its Extremes; fo that how many Octaves foever were puti nto the greateft Syftem, they were

all to be conftjtutcd or fub-divided the fame Way as the Firft ■ So that when we know how the Oclave is divided, we fo " the Nature ofthe'Diagramma or Scale: TheVarieties where of, conftituted the Genera Melodic, which were lub-dividej into Species. See Genera and Species.

SYSTOLE, in Medicine, the Contraction of the Heart and Arteries ot an Animal. See Heart and Artery.

The Syftole of the Heart is well accounted for by D r , Lower, who Ihews, that the Heart is a true Mufcle, the Fibres whereof are ailed on like thofe of other Mufcles by Means of certain Branches of the eight Pair of Nerves inferted into it, which bring the Animal Spirits from the Brain hither. By a Flux of rhefe Spirits, the Muicular Fibres of the Heatt are inflated, and thus fhorten'd; the Length of the Heart diminilh'd, its Breadth or Thicknefs increas'd, the Capacity of the Ventricles clos'd, the ten- donous Mouths of the Atteries dilated, thole of the Veins fhut up by means of their Valves, and the contain'd Juices forcibly exprefs'd into the Orifices of the Arteries. See Muscle.

And this we call the SuroAn, or Contraflion of the Heart; the oppofite State to which is call'd the Diaftole, or Dilata- tion of the Heatt. See Diastole.

Dr. 'Drake adds to Dr. Lower's Account, that the inter- coftal Mufcles and Diaphragm, contribute to the Syftole, by opening the Blood a Palfage from the right Ventricle of the Heart, to the left thro' the Lungs, to which it could not otherwife pafs : By which Means, the Oppofition the Blood contain'd in that Ventricle muft neceffarily have made to its Conftfuction, is taken off'. See Contraction.

Lower and Drake make the Syftole the natural State or ABion of the Hearr, and the ^Diaftole the violent one : Boerhaave, on the contrary, makes the Syftole the violent, and the Diaftole the natural State.

SYXHINDEMEN, a Term purely Saxon, literally fig- nifying 600 Men, or Men worth 600 Shillings.

In the Time of our Saxon Anceftors, all Men were rank'd into three Clafles j the lo-weft, the middle, and the higheft; and were valu'd according to their Clafs: that if any Injury were done, Satistacfion might be made to the Value or Worth of the Man it was done to.

The loweft were call'd Tieyhindanen, q. d. valued at 200 Shillings; the middle, Syxhindemen, q. d. valued, at 600 Shillings; and the higheft, 'Pxelfhindemen, i. e. valued at 1200 Shillings.

SYZIGY, in Aftronomy, a Term equally ufed for the Conjunction and Oppofition of a Planet with the Sun. See Conjunction and Opposition.

The Word is form'd from the Greek, mtyyta., ConjunBio.'

On the Phenomena and Circumftances of the Syzygies, a gteat Part of the Lunar Theory depends. See Moon.

For, i°. It is fhewn in the Phyfical Aftronomy, that the Force which diminifhes rhe Gravity of the Moon in the Syzygies, is double that which increafts it in the Quadrature : So that in the Syzrgies the Gravity of the Moon from the Aflion of the Sun' is diminifh'd by a Part, which is to the whole Gravity as r to 80,36; tor in the Quadratures, the Addition of Gravity is to the whole Gra- vity as i to 178,73. See Quadrature.

2°. In the Syzygies, the difturbing Force is directly as the Diftance of the Moon from the Earth, and inverfely as the Cube of the Diftance of the Earth from the Sun. And at the Syzygies, the Gravity of the Moon towards the Earth, receding from its Centre, is more diminilh'd, than according to the inverfe Ratio of the Square of the Diftance from that Centre. Hence, in the Motion of the Moon from the Syzygy to the Quadrature, the Gravity of the Moon to- watds the Earth is continually increas'd, and the Moon is continually retarded in its Motion; and in the Motion from the Quadratures to the Syzygies, the Moon's Gravity is con- tinually diminilh'd, and its" Motion in its Orbit accelerated. See Gravity.

3 . Further, in the Syzygies the Moon's Orbit or Circle round the Earth, is more convex than in the Quadratures; for which Reafon the Moon is lefs diftant from the Earth at the former than the latter. When the Moon is in the S0 M gies, her Apfides go backwards, or are retrograde. See Oa- bit, Apsides and Retrogradation.

When the Moon is in the Syzygies, the Nodes move '" Antecedentia fafteft; then (lower and flower, till they be- come at reft when the Moon is in the Quadratures, See Node.

Laftly, When the Nodes are come to the Syzyqieli the Inclination of the Plane of the Orbit is leaft of all. ^See In- clination.

Add, rhat thefe feveral Irregularities ate not equal io eac ' 1 Syzygy, but all fomewhat greater in the Conjunction tnan the Oppofition. See Disturbing Force, Jffc,