Thus,

Fig.

The Right Shoulder of Auriga, and the Right Shoulder of XXXIIJ. Orion, being under the fame Meridian, their Distance will be

found to be 37 d. 38 m.

Also,

Arcturus and the Lion's Neck, being near in the fame Parallel, their Distance will be found to be 57 d. Likewife,

Lyra the Harp, and Marchad in the Wing of Pegasus, will be found to be distant 63 d.

The finding of the Distance of Stars upon the Cælestial Globe is the fame as the finding of Distance of Places upon the Terreftrial, and consequently the Triangles made upon the Globe are the fame also: So that the Canons for Calculation for finding them will be the fame also, and needs not be here again repeated.

PROB. XIII.

To know what Stars will be upon the Meridian at any Hour of the Night.

T

HE Sun being in 29 d. of Taurus, what Stars will be upon the Meridian at 10 a Clock, and 12 m. at Night. Bring 29 d. of Scorpio (which is the oppofite Sign to Taurus) to the Meridian, and set the Index of the Hour-Circle to 12. Then turn the Globe about Westward till the Index point at 12m. after 10 a Clcck, and there hold the Globe; and all those Stars which lye under the Brass Meridian are then upon the Meridian, of which Arcturus is the Chief.

This needs no Trigonometrical Calculation.

PROB. XIV.

To know what Day in the Year any Star shall be upon the Meridian at 12 a Clock at Night.

BRing the Star to the Meridian, and mark what Degree of

the Ecliptick is just under the Meridian at the same time: Then find that Degree of the Ecliptick in the Horizon, and note what Day of the Year standeth against it, for that Day of the Year will that Star be upon the South Part of the Meridian at 12 at Night: And when the Sun is in the opposite Point of

L12

the

Fig. the Ecliptick, the fame Star will be upon the North Part of the XXXIII. Meridian at 12 at Noon.

PROB. XV.

The Sun's Place, and the Altitude of a known Star given; To
find the Hour of the Night.

T

HE Sun being in 21 d. of Capricorn, the Altitude of the
Great Dog 14 d. I demand the Hour of the Night.

The Globe Rectified, &c. Bring 21 d. of Capricorn to the
Meridian, and the Index to 12 a Clock. Then move the Globe
and Quadrant of Altitude so together, that the Great Dog meet
with 14 d. of the Quadrant; and then shall the Index point at
8 of the Clock, and 22 m. which is the true Hour of the Night.

D.

And thus,

D.

2012 and the (The Bull's Eye 392 The ho.

When
the Sun 20 M
is in

Π

3

The Bull's Eye 30

tude of Arcturus

PROB. XVI.

50

will be

The Altitude of Aldebaran (or any other Star) being given, in a
known Latitude; To find the Star's Azimuth.

T

HE Quadrant of Altitude being fixed in the Zenith, move it and the Globe till the Degrees of Altitude given do meet with the Centre of the Star; then shall the end of the Quadrant of Altitude shew you upon the Horizon the Azimuth in which the Star then is. And thus, if you bring the Quadrant of Altitude on the East Side of the Globe, moving it and the Globe both, till the Centre of Aldebaran do meet just with 42 d. of the Quadrant, you shall then find the Quadrant. of Altitude to reft at 33 d. of the Horizon, counted from the East; or at 57 d. if you count them from the South: And that is the Azimuth of Aldebaran when he hath 42 d. of Altitude; and that is near the S. E. by E. Point of the Compafss..

The

Fig.

The Latitude of the Place, (51 d. 30 m.) and the Decli- xxxIII. nation of a Star, (Suppose the Bull's Eye, Aldebaran ) given :

To find

PROB. XVII.

Its Right Afcenfion.

HE Globe Rectified to the Latitude, &c. Bring Aldebaran T to the Meridian: Then count how many Degrees of the Equinoctial are contained between the Meridian and the beginning of Aries; which will be 64 d. 17 m. and that is the Right Afcenfion of that Star; which in time (by allowing 15 d. for an Hour, and rd. for 4 m. of time) in 4 h. 16 m. its Right Afcenfion in time.

And in the fame manner may you find

The Right Aridurus

Afcenfi-Sprius

on of

Algol S

D. M.

210 13

to be 97

42

39 39.

}

in time

tim

Н. М.

14 I

6 30

2 38

The fame Trigonometrical Calculation, as for the Sun's Right

Afcenfion, as in Prob. III. serves for this also.

Bring the Starte

PROB. XVIII.

Its Afcenfional Difference.

the Meridian, and the Hour-Index to 12.

Then bring the Star either to the Eaft or West Side of the Horizon, and there you shall find 1 h. and 27 m. contained between the Index and 6 a Clock: And such is the Afcenfional

ference of Algol

to be 21 28 or in time I 26

Algol his Declination being more than the Complement of the
Latitude, never rises nor fets, but is always above the Hori-

zon..

The fame Trigonometrical Calculation, as for the Sun.

PROB

Fig. XXXIII.

PROB. ΧΙΧ.

Its Amplitude.

BRing Aldebaran to the Horizon

on either Side

of the Globe,

and you shall find it to touch the Horizon at 25 d. 56 m. from the Eaft or West Northward; which is the Amplitude of the Bull's Eye rising or setting. And according to the Points of the Compass it riseth E. N. E. 2 d. 26 m. Northerly, and fets W. N. W. 2 d. 26 m. Northerly.

The Semidiurnal Arch, and the time that Aldebaran (or any other
Star) continues above the Horizon.

Bring the Aldebaran to the Meridian, and fet the Hour-Cir

Then turn Globe Westward, till Aldebaran touch the Horizon; then shall the Hour-Index point at 7 h. 27 m. And so long time is Aldebaran above the Horizon, before he comes to the Meridian, and continues so many Hours and Minutes above the Horizon, after he hath past the Meridian, and sets in the West. And those 7 h. and 27 m. is the Semidiurnal Arch of that Star; which doubled, is 14 h. 54 m. And fo long doth that Star continue above the Horizon after the time of his rifing.

And in this manner you find

D. M.

Η. Μ. 15 50 nuance above 9 8

7 552 And his Conti

diurnal Syrius to be 4 34

Arch of Algol

(1200) the Horizon 224 00

The fame Trigonometrical Calculation as for the Sun.

:

PROB. PROB. ΧΧΙ.

At what Hour (any time of the Year) Aldebaran comes to the
Meridian.

Lisin

ET the time be the First of January, at which time the Sun is in 22 d. of Capricorn. Bring 22 d. of Capricorn to the Meridian, and fet the Hour-Index to 12. Then turn the Globe about till Aldebaran be under the Meridian, and then you shall find the Index to point at 42 m. after 8 of the Clock, at which time Aldebaran will be upon the Meridian that Night.

In like manner you may find that

October 287 Arcturus will be upon
Upon Fanuary 21 Syrius
the Meridi
Σ
January
Algol

I

an at

Η. Μ.

II 10

9

33

7

12

The same Trigonometrical Calculation as for the Sun.

PROB. ΧΧΙΙ.

At what Hour (at any time of the Year) Aldebaran (or any other
Star) rifeth or fetteth.

m.

LE
ET the time be January 1. By the laft before-going, you
found that Aldebaran came to the Meridian at & h. 42
And by the last but one you found his Semidiurnal Arch to be
7 h. 27 m. This being taken from 8 h. 42 m. the time of his
being South, leaveth 1 h. 15 m. the time of its rifing; so that
upon the First of January Aldebaran did rise at 15 m. after 1
in the Afternoon. Again, if you add his Semidiurnal 7 h. 27 m.
to the time of its being South 8 h. 42 m. the Sum will be 16
h. 9 m. from which take 12 h. and the Remainder will be 4 h.
9 m. So that Aldebaran did fet at 9 m. after 4 of the Clock the
next Morning.

And in like manner you may find that

October 28) Arcturus
Upon January 21 Syrius
Syrius
1 Algol

January

Rises at

H. M.

53 82

3Setsat

Algol never Rises nor Sets.
The same Trigonometrical Calculation as for the Sun.

H. M.
7

2

12
3

PROB

Fig. XXXIII.

1