The Third Book of the Cross-StaffCHAP. XII.
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Ho. | An. Po. | Tang. | Secant. | 11 30 | 16 55 | 20 12 | 21 41 | 23 30 | ||||||||
Gr. | M. | In. | Pa. | In. | Pa. | In. | Pa. | In. | Pa. | In. | Pa. | In. | Pa. | In. | Pa. | |
0 | 0 | 0 | 0 | 0 | 10 | 00 | 2 | 3 | 3 | 4 | 3 | 68 | 3 | 98 | 4 | 35 |
3 | 45 | 0 | 65 | 10 | 02 | 2 | 04 | 3 | 05 | 3 | 69 | 3 | 99 | 4 | 36 | |
7 | 30 | 1 | 32 | 10 | 09 | 2 | 05 | 3 | 07 | 3 | 71 | 4 | 01 | 4 | 39 | |
11 | 15 | 1 | 99 | 10 | 20 | 2 | 07 | 3 | 10 | 3 | 75 | 4 | 05 | 4 | 43 | |
1 | 15 | 0 | 2 | 68 | 10 | 35 | 2 | 10 | 3 | 15 | 3 | 81 | 4 | 12 | 4 | 50 |
18 | 45 | 3 | 39 | 10 | 56 | 2 | 15 | 3 | 21 | 3 | 99 | 4 | 20 | 4 | 59 | |
22 | 50 | 4 | 14 | 10 | 82 | 2 | 20 | 3 | 29 | 4 | 10 | 4 | 30 | 4 | 70 | |
26 | 15 | 4 | 93 | 11 | 15 | 2 | 36 | 3 | 39 | 4 | 24 | 4 | 45 | 4 | 85 | |
2 | 30 | 0 | 5 | 77 | 11 | 55 | 2 | 34 | 3 | 51 | 4 | 60 | 5 | 02 | ||
33 | 45 | 6 | 68 | 12 | 03 | 2 | 44 | 3 | 66 | 4 | 42 | 4 | 78 | 5 | 21 | |
37 | 30 | 7 | 67 | 12 | 60 | 2 | 56 | 3 | 83 | 4 | 64 | 5 | 02 | 5 | 48 | |
41 | 15 | 8 | 77 | 13 | 30 | 2 | 70 | 4 | 05 | 4 | 89 | 5 | 29 | 5 | 78 | |
3 | 45 | 0 | 10 | 00 | 14 | 14 | 2 | 87 | 4 | 30 | 5 | 10 | 5 | 63 | 6 | 15 |
48 | 45 | 11 | 40 | 15 | 17 | 3 | 08 | 4 | 62 | 5 | 58 | 6 | 03 | 6 | 00 | |
52 | 30 | 13 | 03 | 16 | 43 | 3 | 34 | 5 | 00 | 6 | 04 | 6 | 54 | 7 | 14 | |
56 | 15 | 14 | 97 | 18 | 00 | 3 | 66 | 5 | 48 | 6 | 62 | 7 | 15 | 7 | 83 | |
4 | 60 | 0 | 17 | 32 | 20 | 00 | 4 | 07 | 6 | 08 | 7 | 36 | 7 | 95 | 8 | 70 |
63 | 45 | 20 | 28 | 22 | 61 | 4 | 60 | 6 | 88 | 8 | 32 | 9 | 00 | 9 | 83 | |
67 | 30 | 24 | 14 | 26 | 13 | 5 | 31 | 7 | 95 | 9 | 61 | 10 | 39 | 11 | 36 | |
71 | 15 | 29 | 46 | 31 | 11 | 6 | 33 | 9 | 47 | 11 | 45 | 12 | 37 | 13 | 53 | |
5 | 75 | 0 | 37 | 32 | 38 | 64 | 7 | 86 | 11 | 74 | 14 | 20 | 15 | 36 | 10 | 80 |
78 | 45 | 50 | 27 | 51 | 26 | 10 | 43 | 15 | 60 | 18 | 89 | 60 | 38 | 22 | 28 | |
82 | 30 | 75 | 96 | 76 | 61 | 15 | 58 | 23 | 32 | 28 | 10 | 30 | 47 | 33 | 31 | |
86 | 15 | 152 | 57 | 152 | 90 | 31 | 10 | 46 | 44 | 56 | 26 | 60 | 81 | 66 | 48 | |
6 | 90 | 0 | Infin. | Infin. | Infin. | Infin. | Infin. | Infin. | Infin. | |||||||
As in the former Example of the Polar Plane, where BC the height of the Style is found to be 1 Inch 61 cent. if it were required to find the distance between B the top of the Style, and the Points wherein the Hour-lines of 7 in the Morning or 5 in the Afternoon do cross the Equator (which distances I called the Secants of those Hours) either you may extend the Compasses from the Sine of 15 gr. the Complements of the Hour from the Substylar, unto the Sine of 90 gr. so the same extent will reach in the Line of Numbers from 1.61 the length of the Style, unto 6.21, according to the former Canon. Or else you may make use of the following Table, extending the Compasses in the Line of Numbers from 10.00 the length of the Style in the Table, unto 1.61 the length of the Style belonging to your Plane; so the same extent shall reach from 38.64, the Secant in the Table, unto 6.21, and such is your Secant required, the distance between the top of the Style and the point of Intersection, wherein the fifth Hour-line from the Substylar doth cross the Equator.
Again, the same extent will reach from 16.80 the distance in the Table belonging to the fifth Hour-line between the Equator and the Parallel of 13 gr. 30 m. declination, unto 2.70 for the like distance upon your Plane; and so for the rest, which may be gathered, and set down in a Table.
Hours. | Ang. Po. | Tang. | Secan. | Trop. | |||||
Gr. | M. | In. | Pa. | In. | Pa. | In. | Pa. | ||
12 | 0 | 0 | 0 | 0 | 1 | 61 | 0 | 70 | |
11 | 1 | 15 | 0 | 0 | 43 | 1 | 63 | 0 | 72 |
10 | 2 | 30 | 0 | 0 | 93 | 1 | 85 | 0 | 80 |
9 | 3 | 45 | 0 | 1 | 61 | 2 | 27 | 0 | 99 |
8 | 4 | 30 | 0 | 2 | 79 | 3 | 22 | 1 | 40 |
7 | 5 | 75 | 0 | 6 | 00 | 6 | 21 | 2 | 70 |
The Tangents and Secants in the third and fourth Columns of this Table are taken out of the Tables of the Natural Tangents and Secants, according to the Degrees and Minutes that are in in the second Column of this Table.
That done, and the Equator drawn as before, if you would draw the Tropicks in the Polar Plane, look into the Table, and take 70 cent. on the first Hour, and 80 on the second Hour, and 2 Inches 70 cent. to the fifth Hour from the Substylar, and the rest of these Distances on their several Hour-lines; and then draw a crooked Line through all these Points, so as it makes no Angles, the Line so drawn shall be the Tropick required. In like manner you may draw any other Parallel of Declination.
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