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great, that, ftretching out the Entrances of the Nerves, they would open tnemfelves a PafTage.
With regard to Medicine, Steep is defined, by %oerfoaave t to be that State of the Medulla of the Brain, wherein the Nerves do not receive lb copious, nor fa forcible an Influx of Spirits from the Brain as is required to enable the Organs of Senfe, and voluntary Motion, to perform their Offices.
The immediate Caufe hereof appears to be the Scarcity of Animal Spirits, which being fpent, and requiring fome Time to be recruited, the minute VeflTels, before inflated, become flaccid and fall : Or elfe, 'tis owing to fuch a Freffure of the thicker Blood againft the Cortes of the Brain, as that the Medulla, becoming likewife compreffed by its Contiguity with the Cortex, the PafTage of the Spirits is obftrucled. The natural Caule of Steep is any Thing that may contribute to thefe two. — And hence its Effects are un- derstood : For in Sleep fcveral Functions are fufpended, rheir Organs and Muicles are at Reft ; the Spirits icarce flow through them, therefore there is a lefs Confumption of them j but the folid Villi and Fibres of the Nerves are but little chang'd, but an Equilibrium obtains throughout ; there is no Difference of PrefTure on the Veflels, nor of Ve- locity in the Humours. The Motion of the Heart, Lungs, Arteries, Vifcera, t$c* is incrcafed ; nor is it chang'd or abated by the Aftion of the Senfes, or of volunta- ry Motions : The Effects of which are, that the Vital Humours circulate more ftrongly and equably thro' the Canals, which are now freer, laxer, and opener, as not being compref- fedby theMufcles. Hence the Blood is driven leis forcibly, indeed, into the Lateral Veflels, but more equably 5 thro' the greater Veflels, both more ftrongly, and more equably. Thus are the Lateral Fibres fenfibly filled, as being lels traverfed, and at length remain at reft, with the Juices they have collected : Hence the lateral adipofe Cells become filled and diftended with an Oily Matter. By this means the Circulation, being aimoft wholly perform'din the larger Blood Veflels, becomes gradually llower, and at length fcarce fenlible, if the Sleep be too long continued: Thus, in moderate Sleepy is the Matter cf the Chyle beft converted into Serum ; that, into thinner Humours -. and thofe, into Kourifhmcnt. The Attrition of the folid Farts is lefs con- siderable 5 the cutaneous Secretion is increafed, and all ihe reft diminifh'd. The Parts wore off are now beft fupplied,as an equable, continual Repletion, reftores the Humours, and repairs the Solids, the preventing and difturbingGaufes being then at reft. In the mean Time, that the nutritious Matter is beft prepared 5 there is an Aptitude in the Veflels to re- ceive, and in the Humours to enter, and the Means of Ap- plication, and Confolidation, are at liberty : Hence, a new Production, and Accumulation, of Animal Spirits, in all the Humours, as to Matter, and in the mi nuteft Veflels as to Repletion: The Confequence of which is, an Aptitude for Making) and an In-aptitude for Sleep; fo that upon the firft Occafion the Man awakes. See Nutrition, f&c.
Some of the more extraordinary Pbxnomena of Sleep, yet to be accounted for, are 5 That when the Head is hot, and the Feet cold, Sleep is impracticable : That fpirituaus Liquors firft bring on Drunkennefs, then Sleep: That Ferlpi- ration, during the Time of Sleep, is twice as great as at other Times : That upon Sleeping too long, the Head grows heavy, the Senfes dull, the Memory weak, with Coldnefs, Pituitoufnels, an Indifpofition of the Mufcles for Motion, and a want of Perfpiration. That much Sleeping will fiiflain Life a long Time, without either Meat or Drink: That upon a laudable Sleeps there always follows an Expanflon of all the Mufcles, a repeated Yawning, and the Muicles and Nerves acquire a new Agility : That Fcetuss always peep -j Children often, Youth more than grown Perfons, and they more than old Men ; and that People, riling from violent Diftempers, peep much more than when per- fectly at Health.
SLIDING, in Mechanicks, called, by fome Authors, Superinczffm Radens, is, when the fame Point of a Body, moving along a Surface, defcribes a Line on that Surface : Such is the Motion of a Parallelepiped, protruded along a Plane.
SLIDING RULE, a Mathematical Inftrument, ferving to work Queftions in Gauging, Meafuring, &c. without the Ufe of Compafles; merely by the fliding of the Parrs of the Inftrument one by another, the Lines and Divifions whereof give the Anfwer, by Infpe&ion. See Rule.
This Inftrument is varioufly contrived, and applied by various Authors ; particularly Everard, Coggeflial, Gtmter, Hunt, and Cartridge j but the moft ufual and uleful ones, are thofe of Everard and Coggeflal ; the Defcription, and Ufes whereof, are as follow.
J&erarfs Sliding-Rule is principally ufed in Gauging. See Gauging.
- Tis ordinarily made of Box, a Foot long, an Inch broad,
and f- thick. It confifts of three Parrs ; A Rule, on each Side whereof ah and c d, Tab. Surveying, Fig. 17. is a Groove j and two final! Scales, or Slidiug-'Pieces. m t 72, to
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fidem the Grooves. When both thefe Pieces are drawn o«f to their full Extent the Inftrument is three Foot long.
On the firft k-oad free ot the Inftrument a b, are four Lines of Numbers ; for the Properties,^, whereof fee Line of Numbers. The hrrt mark'd A, confining of two Radius's number d ,, 2 , ? 4, f , g, ?> g) ^ thm
s , &c. to ,0 On thts Line are four Brafs GentrVftn* two in each Kadius ; one in each whereof is mark'd M B< to fignify that the Numbers ',isfet againft, 2,50.40 are the Cubic Inches In aMalt-Bufhcl ; the other two are marked With A, to fignify that the Numbers they are let againft m. 282, are the Cubic Inches in an Ale-Gallon. The lei cond and third Lines of Numbers, are on the Sliding Tieces, and are exaflly the lame with the firft. dole to the Fi- gure 7, m the firft Radius, is a Dot mark'd Si, let di- reflly over 707, denoting 7 o 7 to be the Side of a Square infcribed in a Circle, whole Diameter is Unity Clole to I is another Dot, mark'd Se, let over 886, which is the Side ot a Square, equal to the Area of a Circle, whole Diameter js Unity. Another Dot, nigh \V, is let over 331, .the Number of Cubic Inches in a Wine-Gallon; and another near C, ,s fet over 3.14 the Circumference of a Circle whofe Diameter is Unity. The fourth Line of Numbers, mark'd M D, to fignify Malt Depth, is a bro- ken Line ot two Radius's number'd 2, I0 , 9 , g, - g, „.
4 ' ?' ,?'»«*,?' 8 ' 7' ***• thc Numbers being' let d'lreftW againft M B on the firft Radius. S *
On the fecond broad Face, mark'd c i are 1° A Line of Numbers of one Radius, number'd 1,2 3 and to 10 noted by the Letter D On this are four Centre-Pins, the firft, mark d W G, is the Gauge-Point for a Wine-Gallon 1. e the Diameter of a Cylinder, whofe Height is an Inch, and Content 231 Cubic Inches, or a Wine-Gallon, which is ,7. ,5 Inches: The fecond Centrcpin A G Hands at foe Gauge Point for an A!e-Ga!lon, which is ,8.05 Inches. The third MS ftands at 86.3 the Side of a Square, whole Content is equal to the Inches in a folid Bufhel "The fourth M R. is the Gauge-point for a Malt-bufhcl, which is 52.32 Inches. 2°. Two Lines of Numbers on the Sliding' Vtgce, which are exaflly the lame as thofe on the Sliding. •Pteceo* the other Side. Clofe to the Diviiion 8 is a Dot markd it, which is let to 795. the Area of a Circle, whole Diameter is Unity ; and another mark'd d, ftands at 785, the Area of a Circle, whole Diameter is Unity. 30. Two Lines of Segments, each number'd 1, 2, 3, to ,00-
M" Ji I fc a find [ ng ^ U ' a S e of a Cask *-«k ™ die Middle Fruftum of a Spheroid, lying with its Axis parallel to the Horizon; and the other, for finding the Ulage of a Cask Handing. ° &
Again, on one of the narrow Sides, noted e are 1° A Line of Inches, number'd ,, 2, 3, gfc. to , 2 , each fob- divided into 10 equal Parts. 2°. A Line, by which, with that ot Inches, we find a mean Diameter for a Cask, in the Figute of a Middle Fruftum of a Spheroid: 'Tis number'd 1, 2, 3, p. to 7 and mark'd Spheroid, 3 °. A Line for folding the mean Diameter of a Cask, ,n the Figure of the Middle Fruftum of a Parabolic Spindle, which Gangers call, the Second Vamty of Casks; 'T.s number'd ,,2, 3, Be and noted .Second Variety. 4°. A Line, by which we find the mean Diameter of a Cask of the Third Varielv, i.e. ot a Cask in the Figure of two Parabolic Conoids, abutting on a common Bale; 'tis number'd 1 2 3 £t? c and noted Third Variety. ' ' 3 ' '
On the other narrow Face, mark'd fi are, 1° A Foot di- vided into ,oo equal Parts, mark'd F M. 2°! A Line of. Inches, like that before-mention'd, noted I M 30 A Line for finding the mean Diameter for the fourth Variety of Casks, which is the Middle Fruftum of two Cones, abuttir" on a common Bale It is number'd ,, 3 , 3, {jfc, and noted F C, fignifymg Fruftum of a Cone.
Note, on the Backfide of the two Slidiat-'Pieces are a Line of Inches from 1 , to 36, when the two Pieces are put End- w.le; and againft that, the correspondent Gallons, or Hun- dred Parts, that any fmall Tub, or the like open Veffel (trom 13 to 36 Inches Diameter) will contain at one Inch
Ufe o/Everard'i Seiding-Rule.
i°. To multiply one Number ly another. Suppofe 4 re- quired to be multiplied by 6 : Set 1 on the Line* of Num-
u d'° 4 ° n thc Line A ' then > a g aillft 6 upon B is 24, the Froduft fought upon A. Again, to multiply 26 by 68, fet 1 on B to 26 on A ; then, againft f58 on B is i 7 «« on A, the Produfl fought. '
,.-?• ^° divide one Number by another. Suppofe 24 to be divided by 4: Set 4 on B to 1 on A ; then againft 24 on B is 6 on A, which is the Quotient. Again, to divide ojj by 14; fet 14 on A to 1 on B, and againft o; 2 on A you have on B, 68, which is the Quotient.
3°. To work the Rule of Three. If 8 give 20, what will 22 give? Set 8 on B to 20 on A, then againft '2 2 on B ftands jj on A ; the Number fought.
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