Page:Cyclopaedia, Chambers - Volume 2.djvu/763

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frards the Tefles. By this means, the Blood teceives a Check at its firft going off for thofe Parts, which difpofes it for the future Changes, ($c. it is to pafs. The fame End is anfwered in Quadrupeds, by having theft Arteries curl'd and contorted in tneir Paffage like a Screw.

The Reafon why Nature has taken another Method in Man ; t&t.Cowfer oblerves, is, that in that Cafe, the Abdo- minal Mufdes mull have been much larger than they are ; by which means, the Interlines would have been frequently let down into the Scrotum ; an Inconvenience Quadrupeds arefecured from, by the horizontal Pofition of their Bodies.

The fpermatic Arteries, in their Frogrefs, meeting with the fpermatic Feins, enter together with them the inner La- mella of the Peritoneum, where, infinuating into the Du- plicature of the Procels, and being cloathed thetewith, they pafs on to within three or four Fingers Breadth of the Tefticles, where they divide into Two unequal Branches ; the biggeft of which, goes to the Tefticle, and isdiftributed thetein (See Testicle.) And the lefs in the Paraflata or Epididydimis. See Parastata.

The fpermatic Veins take the fame Conrfe with the Ar- teries ; only a little above the Tefticles, they fplit into fe- veral Branches, which uniting, form a Plexus, called Carpus Vttricofimt 'Pampiniform or Pyramidale. The Blood re- turned by the fpermatic Feins, is delivered on the right Side to the Cava, and on the Lefr, into the emulgent Vein.

SPERMATOCELE, in Medicine, a Rupture occafioned by a Contraction of thefeminal Veffels, whereby they ate let fall into the Sctorum. Harris.

SPHACELUS, in Medicine, a total Mortification of any Part, occafioned by an Interception of the Blood and Spitits. See Mortification.

The Word is Greek, rQthx\@; form'd, perhaps, of cr$*Tj-"»i

nm.

The Sphacelus is diftinguifhed from the Gangrene; which is only a Mortification begun, and, as it were, the Road to a Sphacelus, which is the State and Perfection thereof. See Gangrene.

The Sphacelus is diftinguifhed by the Lividnefs or Black- nefs of the Part affected ; its Softnefs, Infenfibility and ca- daverous Smell.

The other Caufes of the Sphacelus, Site clofe Ligatures, cxceflive Colds, great Inflammations, Bites of Mad Dogs. "Tis fometimes, alfb, called Necrojis, and fotnetimes Sidero- tic-. See Necrosis and Sideratio.

A Sphacelous Foot, according to Aqiiapenimte, ought to be cut off in the mortified Part, near the live Patt. When the Foot is off, the dead Flefh left behind, is to be confumed by the Application of an actual Cautery, repeated feveral Times, till the Patient feel the Heat of the File. Scultet.

SPHJE.RISTER1UM, in Antiquity, the feventh Part of the ancient Gymnafium ; being that wherein the Youth practi- ced Tennis-Playing. See Gymnasium.

The Sphtcrifterium or Tennis-Court, was between the Place, named Palieftra, and that where they run Races, which was between the Portico's and the outer Wall : Though Vitruvius does not make mention of it in the Defcription he gives of the ancient Gymnafium.

The Exercife here perform'd was called Sphteriflicz and Sphceromachia, which fbme will have to have differ'd from the modern Tennis 3 but 'tis not known wheiein the Diffe- rence confiiled.

The Milefians were particularly averfe to this Exercife ; and the Athenians as remarkably fond of it.

They frequently gave the Right of Citizens to the Sphte- rifles, or Mailers in this Art, by way of Refpect.

SPHENOIDAL Suture, in Anatomy, a Suture thus call'd, from its encompaffing the Os Sphenoides, which it feparates from the Os frmtis, the Ospetrofum and Os occipitis. See Suture.

SPHENOIDES, in Anatomy, a Bone of the Head, com- mon to the Cranium and upper Jaw. See Cranium, &c.

It is fituate in the lower Part of the Skull, whereof it is, as it wete, the Bafis, and is connected to all the other Mem- bers thereof, by the Sphenoidal Suture. Its Form, is irregu- lar, and not eafy to be defcribed ; whence fbme have call'd it Multiforme. It has its Name Sphenoides from the Greek, ff$m, Cuneus, Wedge, from the Form of its Infertion into the other Bones of the Skull.

In Adults, 'tis one continued Bone ; but in young Childten, fometimes conlifls of Three, and fomatimes of Four diftinct Pieces.

SPHENOSTAPHTLINUS, in Anatomy, a Mufcle of the Larynx. It defcends from a round, flefhy Origination, near the Root of a Procefs of the Os Sphencides, and is im- planted into the pofterior Part of the Uvula, where it joins its Partner. It ferves to draw the Uvula upwards and back- wards ; and hinders the mafticated Aliment from palling into the Foramina Narium in Deglutition.

SPHERE, in Geometry, a Solid Body contained under one fingle Surface, and having a Point in the middle, call'd the Centre, whence all the Lines drawn to the Surface, are equal. See Sour, &c.

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The Sphe're is fuppofed to be generated by the Revolution of a Semi-circle, as K, (Tab. Geometry Fig. 34.) about its Diameter A B, which is alio called the Axis of the Sphere, and the extreme Points of the Axis, A and C the Poles of the Sphere. See Centre, Circumference, Axis, Pole, Sfc.

(Properties of the Sphere.

1° A Sphere is equal to a Pyramid, whofe Bafe is equal to the Surface, and its Height to the Radius of the Sphere.

Hence a. Sphere being efteem'd filch a Pyramid, its Cube or Solid Content, is found like that of a Pyramid. See Pyramid.

2? A Sphere is to a Cylinder, Handing on an equal Bafis, and of rhe fame Height, as2 to 3. Hence, alio, may the Cube or Content of the Sphere be found. See Cylinder.

3 The Cube of the Diameter of a Sphere, is to the Solid Content of the Sphere, neatly as 30010157: And thus, alio, may the Content of the Sphere be meafured.

4 The Surface of a Sphere is quadruple that of a Circle delcribed with the Radius of the Sphere. For fince a Sphere is equal to a Pyramid, whofe Bale is the Surface, and its Alti- tude, the Radius of the Sphere : The Surface of the Sphere is had, by dividing its Solidity by a third Part of its Semi- diameter.

If, now, the Diameter of the Circle be 100, the Area will be 7850; confequently, the Solidity 1570000, which divided by a Third of the Semi-diameter, 100 ; the Quo- tient is the Surface of the Sphere 3 1400 ; which is manit'eftly quadruple the Area of the Circle.

The Diameter of a Sphere ieingghen, to find its Surface and Solidity.

Find the Periphery of the Circle defcribed by the Radius of the Sphere. See Periphery.

Multiply this, found, into the Diameter; the Product is the Surface of the o^/:we. Multiply the Surface by a fixth Part of the Diameter, the Product is the Solidity of the Sphere.

Thus, fuppofing the Diameter of the Sphere 56, the Peri- phery will be found 175; which multiplied by the Diameter, the Product 9800 is the Surface of the Sphere ; which mul- tiplied by one fixth Part of the Diameter, gives the Solidity 919057. Or, thus ;

Find the Cube of the Diameter 175616; then (0300157, and the Cube found, find a Foutth proportional, 919057. See Proportional. This is the Solidity of the Sphere required.

For Segments and Sectors of Spheres ; fee Segment and Sector.

Doclrine of the Sphere j„ jSphericks. 'ProjeBionoftheStHE&s. 5 ee £ Projection.

Sphere of Activity of any Body; is that determinate Space or Extent, all round about it, to which, and no farther, the Effluvia continually emitted from that Body, do reach, and where they operate according to their Nature. See Effluvia.

Thus we fee the magnetical Effluvia have certain Bounds and Limits, beyond which they will have no Influence to turn, orattracl the Needle : But where-ever a Needle is placed, fo as it may be moved by a Load-ftone, it may be faid to be within the Sphere of Activity of the Stone. See Macnet.

Sphere, in Aftronomy, that concave Orb or Expanfe, which invefts our Globe, and in which the heavenly Bodies, Sun, Stars, Planets and Comets, appear to be fix'd, at equal Diftances from the Eye. See Heavens.

This is alfb call'd the Sphere of the World; and is the Subjeft of the Spherical Aftronomy. See Spherical, Aflronomy.

This Sphere, as it includes the fix'd Stars, whence we alfb occafionally call it, the Sphere of the fix'd Stars, is vaftly grear. The Diameter of the Earth's Orbit is fb finall, in refpeft of the Diameter hereof, that the Centre of the Sphere is not fenfibly changed by any Alteration of the Spectator's Place in the feveral Parts' of the Orbit : But ftill, in all the Points of the Earth's Surface, and at all Times, the Inhabitants have the fame Appearance of rhe Sphere^ that is, the fix'd Stars feem to poflefs the fame Points in the Surface of the Sphere. For our Way of judging of the Places, £gc. of the Stats, is to conceive right Lines drawn from the Eye or the Centre of the Earth, through the Centres of the Stars, and continued thence, till they cut the forefaid Sphere ; the Points where rhefe Lines terminate therein, are the apparent Places of thofe Stars. See Place and Parallax.

The better to determine the Places of the heavenly Bodies in the Sphere ; feveral Circles are imagined to be defcribed in the Surface thereof; hence called Circles of the Sphere. See Circle of the Sphere.

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