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CHAP. X. How to make a most Ʋseful Instrument of the Stars, and by it to know most readily when any of 31 of the most notable Stars will come to the Meridian, what Hour of the Night, at any time of the Year, at the first sight.

THis Instrument consisteth of two parts, which is two Rundles; on the back side of the foregoing Nocturnal it may be very fitly made: On the matter or greater Rundle are three Circles divided; the outermost is the 12 Months of the Year, begun the 10th of March, the day the Sun enters into Aries; and the Days equally divided to the Number of Days in each Month. The second Circle re∣presenteth the 24 Hour Circle, divided equally into 24 Hours, ½ and ¼, beginning the 10th of March at 12 a Clock at Noon, the time the Sun comes to the Meridian, and the first Degree of Aries. The third and inward Circle is the Aequinoctial, divided into 360 Degrees; by them is accounted the Right Ascension of these 31 Stars in the Table following.

A Table of the Longitude, Latitude, Right Ascensions, and Declinations, of 31 of the most Notable Fixed Stars: Calculated from Tycho his Tables, rectified for the Year of our Lord, 1671.

	Longitude.	Latitude.	Ascensi∣on.	Decli∣nation.	Nor. Sou.
The Whale's Tail	27 56 ♓	20 47 S	06 45	19 48	S	2
The Bright Star in the South Foot of Androm.	09 39 ♉	27 46 N	25 57	40 44	N	2
The Bright Star in the Right Side of Perseus.	27 17 ♉	30 05 N	44 16	48 36	N	2
The Bright Star of the 7 Stars or Pleiades.	24 24 ♉	04 0 N	52 00	23 03	N	3
The South Eye of the Bull Aldebaran.	05 12 ♊	05 31 S	64 17	15 48	N	1
The Bright Star in the left Foot of Orion Riges.	12 17 ♊	31 11 S	74 44	8 37	N	1
Orion's right Shoulder towards the East.	24 12 ♊	16 6 S	84 23	07 18	N	1
The glittering Star in the Mouth of the great Dog.	09 35½ ♋	39 30 S	97 42	16 14	S	1
The Little Dog's Thigh Procyon.	21 18½ ♋	15 57 S	110 34	06 03	N	2
In the South Arm of the Crab.	09 03½ ♌	05 08 S	125 22	20 48	N	3
The Bright Star called the Heart of the Hydra.	22 45 ♌	22 24 N	137 54	07 15	S	1
The Lion's Heart Regulus.	25 17 ♌	00 26 N	147 43	13 33	N	1
The lower of the Pointers.	14 43 ♌	45 03 N	160 18	58 08	N	2
The White or North Pointer.	10 34 ♌	49 40 N	160 48	63 32	N	2
The Lion's Tail.	17 03 ♍	12 18 N	173 04	16 25	N	1
The First between the Tail and the Body.	04 10 ♍	54 18 N	189 03	57 47	N	2
The second of the Tail of the Horses.	10 56 ♍	56 14 N	197 37	56 41	N	2
The Fore-Horse, or last in the Tail.	22 12 ♍	54 25 N	203 37	51 00	N	2
In the Skirt of his Garment Arcturus.	19 39 ♎	31 2½ N	210 13	20 58	N	1
The South Balance of Libra.	10 31 ♏	00 26 N	218 13	14 37	S	2
The Brightest of the Guards.	08 16 ♌	72 51 N	223 37	75 38	N	2
The Scorpion Heart Antares.	08 13 ♐	04 27 S	242 23	25 37	S	1
Engonasis Head Hercules.	11 31 ♐	37 23 N	254 12	14 50	N	3
The Bright Star of the Harp Lyra.	10 43 ♑	61 47 N	276 27	38 30	N	1
The Swan's Bill.	26 44 ♑	49 02 N	289 23	27 18	N	3
The Bright Star the Eagle's Heart.	27 09 ♑	29 21½ N	293 41	08 03	N	2
The Dolphin's Tail.	09 32 ♒	29 08 N	304 24	10 14	N	3
The Mouth of Pegasus the winged Horse.	27 22 ♒	22 7½ N	322 03	08 24	N	3
The Bright Star of Pegasus Neck.	1 39½ ♓	17 41 N	336 21	09 08	N	3
The Southern Star in the Wing of Pegasus Macrobe	18 56½ ♓	19 26 N	342 07	13 28	N	2
Andromeda her Head.	09 47 ♈	25 42 N	357 54	27 18	N	2

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On the other Rundle or upper part, is placed all these aforesaid Stars; and any other you may set thereon, if you follow this Rule.

For Example, First set the Index to the 10th day of March of the upper Circle; on the under Circle, which will be at 12 a Clock at Noon, or 360 Degrees, stop it fast there, that it may not move, until you have placed the Stars on it as you intend to set thereon. As suppose you would set the Whale's Tail on the Rundle in his place; look in the foregoing Table, and you will find his Right Ascension 6 deg. 45 min. account that from the 10th of March, and on the Aequinoctial Circle, and lay a Ruler from the Center over the 6 deg. 45 min in the Matter and Aequator or inward Circle, and draw the Line from the Center to the outward Edge of the upper Circle, and thereon set the Name of the Star, next to that the Declination of the Star, and the Letter S or N. representing South or North Declination: on the inward Circle, set before each Star the Magnitude of the Star, whereby you may know the better, as the Figure following shews you all plain.

Take this Example more. Suppose you would set the Lion's Heart in his place; In the Tables I find his Right Ascension is 147 deg. 43 min. reckon that Number on the Aequinoctial Circle next the Rundle, and draw the Line as before-directed, 1 signify∣ing the First Magnitude, secondly his Name, thirdly 13 deg. 33 N, for his North Declination.

The Instrument in this posture, you will find the Lion's Heart will come to the Meridian at almost 10 a Clock in the Evening the 10th day of March in any Lati∣tude.