Page:Cyclopaedia, Chambers - Volume 1.djvu/703

 EQU

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EQU

Theory of the Moon ; wherein we are furnifli'd with For Performance whereof, we fubjoyn the following Equations for all the Inequalities of the mean Motion. Table ; wherein are exhitcd the Arches of the Equator The principal are, ^ ^ which pafs the Meridian in the feverai Hon-,, Minutes'

Sec Equation of

Annual Equations of the mean Motion of the Sim (S c . of Equated, or mean Time, anil Moon, and of the Apogee and Nodes of the Moon. Time. The Annual Equation ol the mean Motion of the Sun, depends on the Eccentricity of the Earth's Orbit round the Sun, which is i(T ji of fuch Parts, whereof the Earth's mean Diftance from the Sun is icoo : Whence its Deno- mination of Equation of the Centre. This, when greateft, is i Deg. 5«' 10' 1 . The greateft Annual Equation of the Moon's mean Motion is n'49"; That of her Apogee 20': And of her Node 9' 30".

Which four Annual Equations are always mutually pro- portional one to another : Wherefore, when any of them is at the greateft, the other three will alfo be greateft ; and when any one leflens, the other three will alfo be diminifhed in the fame Ratio.

The Annual Equation of the Sun's Centre being given, the three other correfponding Annual Equations will be alfo given ; and therefore a Table of that will ferve for all. For if the Annual Equation of the Sun's Centre be taken from thence, for any Time, and be called P, and let f„P (Tab Aftronomy Fig. 51.) = Q, Q.+ i. Q_= R, i P = D, D +, x D = E, and D — i. D = 2 F ; then mall the Annual Equation of the Moon's mean Motion for that Time be R, that of the Apogee of the Moon will be E, and that of the Node F.

Only obferve, that if the Equation of the Sun's Centre be required to be added ; then the Equation of the Moon's mean Motion muft be fubftracfed, that of her Apogee mull be added, and that of the Node fubducled. And on the contrary, if the Equation of the Sun's Centre were to be fubducled, the Moon's Equation mull be added, the Equa- tion of her Apogee fubducled, and that of her Node added.

There is alfo an Equation of the Moon's mean Motion, , depending on the Situation of her Apogee in Ref'pea of M,n, utes > 4°i againft 5 Mmute, l,"cf : Agamft 5 the Sun ; which is greateft, when the Moon s Apogee is in an Oclant with the Sun 5 and is nothing at all, when it is in the Quadratures, or Syzygies. This Equation, when greateft, and the Sun in <Perig<eo, is 3 Min. 5*7 Seconds. But if the Sun be in Apogceo, it \v ill never be above 3 Min. 34 Seconds. At other Diftances of the Sun from the Earth, this Ef}iiation, when greateft, is reciprocally as

Convcriion of Parts of

the Equator into Time

and vice verfa.

Deg. of

Equat.

Hours.

I

Hours.

Deg. of

Equat.

Hour. Min.

Deg. of

Equat.

I

Min.

II

Sec.

II

Sec.

II

III

Third.

III

Third.

III

IV

Fourth

IV

z

4

1

15

I

15

2

8

2

30

z

30

3

12

3

45

3

45

4

16

4

So

4

1

5

20

5

75

5

1

15

10

40

S

90

S

1

30

15

1

9

135

10

2

30

30

z

12

180

20

5

60

4

15

225

30

7

30

90

6

18

270

40

TO

180

12

21

3*5

5°

12

30

36b

24

24

3 So

60

15

The Ufe of the Tabic is obvious ; fuppofc, e. gr. it

were required to turn 19 13'' 7" of the Equator into

Time: Agrdnft 15 Deg. in the Srft Column, we have

Againft 4 Deg. we have i6( o" : Againft 10

Se- conds, we have o" zd" 5 and againft 2 Seconds, W : Which added together, give i h 16' 52'' 28^.

Again, fuppofe it were required to find how many De- grees, Minutes, &c. of the Equator, anfwer to 23 Hours 25 Min. 17 Sec. and 9 thirds. Againft 2i h in the fourth Column of the Table you have 315 : Againft 2 Hours,

30 : Againft 20', 5 -■ Againft 10 Sec, z' 30": Againft

the Cube of fuch Diftance. But when the Moon's Apogee 5 &*•£ «5* V'; Againft z Sec. 30" d" ; againft 6 Thirds, . ^- ..■*«" ac'" ■ Which added together give 351 19 if 15.

"ovation, or Altitude of the Eqjjator, is an

is any where but in the Octants, this Equation grows lefs, ° £1 : Wnicii and is moftly at the fame Diftance between the Earth and IheEkvam. Sun, as the Sine of the double Diftance of the Moon's At< : h °* yattc

al Circle, intercepted between the Equator

A the Horizon. The Elevation of the Equator, with that of the Pole, is always equal to a Quadrant. See Elevation.

EQUERY, or ECURY, a grand Stable, or Lodge for Horfes, furnifhM with all the Convcniencies thereof 5 as Stalls, Manger, Rack, Be.

Some hold that Stable, in Propriety, relates only to Bullocks, Cows, Sheep, Hogs, Sc. And Equery to Horfes, Mules, £?£.

A fimfifa Equery, is that provided for one Row of

Horfes : A double Equery is that provided for two, with

a Paffage in the middle, or two Paflages ; the Horfe?

ture ; and at greareft, is butr 4 7 Seconds'. "This STbe being placed He^d to Head : As in the little Equery at

added to the Moon's mean Motion, while the Nodes are ^erjaiues. _ ,

Under Equery is fometimes aI<o comprehended the Lodgings, and Apartments, of the Equeries^ Grooms, Pages, cjTc. .

The Word is form'd from the French Efcurie, which fignifies the fame Thing. Some, again, derive Efcurie from the Latin ScW'ia, which is not only a Place for

Apogee, from the next Quadrature or Syzygy, to the Radius. This is to be added to the Moon's Motion, while her Apogee paflcs from a Quadrature with the Sun to a Sy- zygy j but is to be fubftracfed from it, while the Apogee moves from the Syzygy to the Quadrature.

There is, moreover, another Equation of the Moon's Motion, which depends on the AfpecT: of the Nodes of the Moon's Orbit with the Sun : And this is greateft, when her Nodes are in Octants to the Sun, and vahiJh.es quite, when they come to their Quadratures or Syzygies. This Equation is proportional to the Sine of the double Diftance of the Node from the next Syzygy, or Quadra-

paffing from their Syzygies with the Sun, to their Qua- dratures with him ; but fubftracied while they pafs from the Quadratures to the Syzygies.

From the Sun's true Place take the equated mean Motion of the Lunar Apogee, as was above ihewed ; rhe Remainder will be the Annual Argument of the faid

T" n l u -d *■■*!■ *;„„ m*m on/1 Beafts to be put up m, but alio a Cjrange, or Barn. But

Apogee. From whence the Eccentricity of the Moon, and ■" r r . > r t» ?.

ffi ficond Elation of her Apogee may ke compared. ^more probable Derivation » from Eqmle, a Stable for

EQUATOR, or vEqjator, in Attronomy, and Geo- H «* s > of E l'" HOTfe ; -

graph?, a great moveable Circle of the Sphere, equally _ E *- UE /^ f*W "*»Ofe.* *»». <*? dillant fron? the two Poles of the World, or having the Care and Management of the Horfes of a Kmg or Pr

- ,,„,„■ Of thefe Equeries, there are a great Number in

fame Poles with thofe of the World. See Circle.

Such is the Circle D A, (Tab. Aftrouom. Fig- 52-) its Poles being P and Q.

It is call'd the Equator, by Reafon when the Sun is therein, the Days and Nights are Equal ; whence alfo it is call'd the Eqllinoclial - ? and when drawn on Maps, and Planifpheres, the EquinoSial Line, or limply the Line, See Equinoctial.

Every Point of the Equator is a Quadrant's Diftance from the Poles of the World ; whence it follows, that the Equator divides the Sphere into two Hemifpheres, in one of which is the Northern, and in the other Southern Pole. See Hemisphere.

By the Paffages, or Tranfits of Arches of the Equator over the Meridian, its equal or mean Time is cllimated : Hence we have frequent Occafion for the Converfion of Degrees of the Equator into Time ; and, again, for the Re-convcrfion of Parts of Time into Parts of the Equator.

■mce. the King of France's Service : As the "Grand Ecuyer, call'd abfolutely Monfieur le Grand ; one of the principal Of- fices of the Crown, and a Branch of that of Conilable 5 anfwering to the Mailer of Horfe among us. He has the chief Intendancc and Direction of the great and little Ecurie, and difpofes of all the vacant Pods therein : the firjl great Ecuyer of the great Ecurie, who has toe Command thereof in the Abfence of the Grand Ecuyer : The firfi Ecuyer of the little Equeries call'd abfolutely Monfieur le 'Premier ■ Ecuyer Cava!ca-hi:r, who com- mands the Equery of Horfes for a Prince's own Riding : Ecuyer de Main, who not only directs the Ecurie, but alfo attends his Mailer in walking, iSc. call'd alfo Gentlemen- Ufliers, and Chevaliers d' Homiciirs : Ecuyer Trenchant, the Kind's Carver and Server : Ecuyer 'Bouche, who ranges the Dimes and Plates on the Table : Ecuyer de Caifine, Sic,

Yjt Eqi'ERIES,