Page:Cyclopaedia, Chambers - Volume 1.djvu/445

 COM

Composition, in Commerce, a Contrail: between an in- Iblvent Debtor and his Creditors; whereby the latter agree to accept of a Part ot the Debt, in compensation for the Whole, and give a general Acquittance accordingly.

COMPOSSIBLES, CompoJJibiiia, in Logick, Yuch Things as are compatible, or capable of fubfifting together.

COMPOST, in Agriculture and Gardening, a Compound, or Mixture of Earths, Dungs, &c. applied, by way of Ma- nure, for the meliorating and improving of Soils, and affift- ing the natural Earth in the Work of Vegetation. See Ma- nure..

The Gardeners have Magazines, or Layftalls of Compofis, adapted to the different forts of Soil. Light loofe Land re- quires a Compofl of a heavy Nature; fuch as the fcouring of Ditches, Ponds, i£c. rnix'd with Earth, Dung, ££p. A heavy, clayey, or cloddy Land requires a Compofi of a more fprightly and active Kind, to insinuate into the heavy, lum- py Clods ; as Dungs, Sand, Ames, and natural Mould.

Mr. Bradley prefcribes feven different forts oi Compojls, to forward the growth of Trees ; viz. a quantity of {tiff Soil, broke, and mix'd with fharp Sand, and Ames of burnt Furzes, Weeds, t$c. or ItiffSoil with Sand and burnt Grafs- turf, and rotten Wood ; or {tiff Soil with Sand and Rape- feed, after the Oil is prefVd out, with burnt Turf; or ftiff Soil with Sand and Malt-grains ; or Sheeps Dung, with Wood Allies and Loam, or Mother Earth. See Soil.

The fame Author recommends a Mixture or Preparation of Soils anfwering to Loam, or Mother Earth, as preferable for planting or fowing Foreft-Trees in, to any of thefe richer Compofis ; which, rho they halten the Growth of the Tree, will not make the Timber near fo firm and durable. See Timber.

COMPOUND, theRefult or Efireft of a Compofition of different Things^, or that which arifes therefrom. Sec Com- position.

Strictly fpeaking, every new Compofition does not produce a new natural Compound ; but only that from which a new ErTence arifes. Thus, when one drop of Water is added to another, there does not arife a new phyfical Compound 5 the Eflence being the fame now, as before the Union.

Compound Flowers, call'd alfo Compojite, and Aggregate % arc fuch as confift of many little Flowers, concurring to make irp one whole one ; each of which hath its Style, Sta- mina, and adhering Seed, hut are all contained within one and the fame Calyx, or Perianthium. See Flower.

This compounded Flower diftingui/hes a large Genus of Plants, which Mr. Ray divides thus :

Herbs of compounded or aggregated Flowers, are,

iff, Such as have a plain-leav'd Flower naturally, and for the moft part full ; and having their whole Body milky, (yielding a milky Juice on cutting them;) and thefe have their Seeds,

Firft, Pappous, or Winged $ that is, having a little La- nugo adhering to each Seed, by which the Wind can ealily carry it from place to place : Such as the La&ttca, Irago- pogon, Scorzonera % fDenS Leonis, Hieracium, and the c Pi- tofclla.

Secondly, Such as have a folid Seed, without any <Pappus or Down upon them ; as the Eringiam Lutcura, Cichorium, Lampfana.

ad, Such as have a difcous Flower ; i, e. one compofed of many ITiort, thick, compreffed, fmall Flbfculi (which fome, by miflake, call Stamina) let together, fo as to make one flat^ or hollowilh Superficies : And thefe are alfo either fuch as have their Seeds,

Firff, Tappous, as the TuffUago, Tetafitcs, Carlina, Se- lenium, fDoronicum, Conyz-a, After, Jfirga Aurea, Jacohdea, Stdtcbas Citrinii Jacca, Scnecio, Eupatorium Avicenng, Cacalia Valgaris, Gnapkalium Maritimum, and Monfpeli- enfiam.

Secondly, Such whofe Seeds are folid, and not pappous 5 as the Corymbiferous Herbs.

Compound Motion, that effected by feveral confpiring Powers. See PoweU.

Kow, Powers are faid to confpire, if the Direction of the one ben't directly oppofite to that of the other ; as when the Radius of a Circle is conceiv'd to revolve about a Cen- tre ; and at the fame time a Point to move {trait along it t

All curvilinear Motion is compound.

'Tis a popular Theorem, in Mechanicks, that in an uniform compound Motion, the Velocity produe'd by the confpiring Powers, is to that of either ot the Powers feparately, as the Diagonal of a Parallelogram, according to the Direction of whofe Sides, they acl: feparateiy ; to either of the Sides. Scg Motion, and Diagonal.

Compound Pendulum, in Mechanicks, that which confiffs of feveral Weights conltantly keeping the fame Diftance, both from each other, and from the Centre about which they ofcillate. See Pendulum.

Compound Ratio, or Proportion. A Proportion is faid to be con/pounded of two or more others, which the Fa&um of two or more Antecedents of Ratios has to the Faftum of

C 291 5

C OM

their Cunfequents : Thus, a to 72 is in a Ratio compiundii of 2 to 6, and 3 to 12. See Proportion.

Compound Quantities, in Algebra, are fuch as are cori- heflcd together by the Signs -f and — ;and are eSprefs'd by the fame Letters equally or unequally repeated : Thus; a + * — c, and t b — b are compound £humtitiest See Quantity.

Compound Numler's, are thofe which may be fneafur'dj ' or exaffly divided, by forne other Number' befide Unity; See Number.

Such is 15 ; which is meafured by 3 and alfo by 5:

Compound Interefi, call'd alfo lutcreft upon Interefi, is that which is reclcon'd not only upon the Principal, but up- on the Intercft it felf forborn ; which hereby bceomes a fort of fecondary Principal. See Interest.

Compound Machine. See Machine.

Compound Rule of Three, See Rule of 'fhree.

COMPREHENSION, in Mctaphyficks, the A& of the Mind, whereby it apprehends or knows any Object ptefented to it, on all the Sides whereon it is capable of being appre- hended, or known. See Apprehension, and Knowledge;

To comprehend a thing, is defined by the Schoolmen, rem alitjuam totam t$ totalitcr cognofcere : And, in this Senfe, 'tis a popular Point of Controvcrfy among the School- Divines, whether the Sleffed in Heaven comprehend God > The more Orthodox maintain the Negative, by reafon fuch Knows ledge muff be infinite.

Comprehension, in Rhetorick, a Trope, or Figure whereby the Name of a Whole is put for a Part ; or that of a Part for a Whole : or a definite number of any Thing for an indefinite. See Metonvmia.

COMPRESS, in Chirurgery, a Bolfter of linen Cloths folded in feveral Doubles, and laid under the Bandages, to prevent a Wound from bleeding or fwelling 5 or to retain the Medicines applied thereto. See Wound.

Scultetus, in his Arfenal of Chirurgery, obferves, that the Antients compos 'd their Compreffes of carded Flax, or of Feathers, few'd between two Linens ; and called them Pillows, or 'Plumages.

The Word comes from Comprimere, to prefs hard.

COMPRESSION, the Aft of preffing or fqucczing fome= thing, fo as to fet its Parts nearer each other, and make it poffefs lefs fpace. See Pression.

CompreJJion differs from Condenfatiov, in that the latter is perform 'd by the Aflion of Cold, the former by fome exter- nal Violence. See Condensation.

Thus, we fay, that Pumps, which the Antients imagin'd to act by Su&ion, do, in reality, aft by CompreJJion ; the Embolus, or Sucker, in going and returning in the narrow Pipe, compreffes the Air jnclos'd therein, fo as to enable it by the Force of its Elaflicity to raife the Valve, and make its efcape : upon which, the Balance being defiroy'd, the Preffure of the Atmofphere on the flagnant Surface, drives up the Water into the Pipe thus evacuated of its Air. See Pump,

Water is incapable of Comprejjim ; after the Air has been purg'd out of it, no Art or Violence is able to bring its Parts clofer, or make it take up lefs compafs. In an Experi- ment made by the Academy dc el Cimento, Water, when violently fqueez'd, made its way thro' the infinitely fin® Pores of a Ball of Gold, rather than undergo Comprejfiotu See Water.

T"be Compression of the Air, by its own weight, is fur- prizingly great : It appears, by Calculation, that the com- mon Air we breathe, near the Sutface of the Earth, is com- prefs'd by the Weight of the fuper-incumbent Atmofphere, into Tf?S v part of the fpace it would take up were it at liberty. See Atmosphere.

But the Air may be Hill further comprefs'd by Art • and it appears from Mr. Style's Experiments, that the Spaca which the Air takes up, when at its utmoft Dilatation, is to that it takes up when moll cmnprefs d, as five hundred an- fifty thoufand to one. See Air.

This immenfe Compreffion and Dilatation, Sir Ifaac Ne-zv- ton obferves, cannot be accounted for from fuppofing the Particles of the Air claftick and branched, or in form of (len- der Twigs interwoven into Circles ; nOr any other way, but by a repelling Force, wherewith they are endued ; by virtue whereof, when at liberty, they mutually fly each other. Sees Attraction.

This repelling Power, he adds, is (Ironger and hiore fen- fible in Air, than in other Bodies 5 in regard Air is gene- rated out of very fix'd Bodies, but not without great diffi- culty, and the help of Fermentation : Now thofe' Particles always recede from each other with the grejtelt violence^ and are comprefs'd with the greateff difficulty, which, when contiguous, cohere the mod ffrongly. See Light.

That there is fuch a repelling Pwxer, appears from this 5

that Flics walk on. the Water without wetting their Feet-

that the Obiedr-GlarTes of Telefcopes laid on each other dri

not touch ; that dry Duff it not brought to touch or cohers

3 Witfe