Table showing the Number of Feet subtending an Angle

of l' at given distances to 32 Nautical Miles.

One foot subtends an angle of l' at a distance of 3437-75 feet.

This table shows the error in height which would result from an error of 1' (and, by multiplication, of any small number of minutes) in the angle of elevation. It also gives, by simple proportion, the height of any object, whose distance from the observer is known, that does not subtend a vertical angle extending 4°; and, vice versâ, the distance of any object whose height is known may also be determined.

If length instead of height is required or known, care must be taken that the object used (for instance a ship) lies broadside on to the observer.

The length of an arc = No. of degrees × radius × 07145.

Table for correcting Longitude by Chronometer for error due to having used an approximate Latitude.

Compiled by LIEUT. J. F. STUART, R.N.

Change of Longitude in miles, due to a change of one mile of Latitude.

II.

to. to to. to. to. to. to. to. to. to. to. to. to. to. to. 90. 90. 90, 90. 90. 90. 90, 90. 90. 90. 90, 90, 90, 90, 90. 60, 60, 60, 60. go, go, go, go, go. 8o. 8o. 8o. 8o. 8o. 8o. ΟΙ ΟΙ ΟΙ, ΟΙ, ΟΙ. II. OI. II. II.

ΟΙ.

OI.

Azi

muth

89

'02 '02 '02 02 02 '02 '02

10

85

84

83

82

*12 12 *12 *12

12 12 13 13 13 13 14 14 14 14 14

14 14 15 15 15 15 16 16 16

LI.

61.

61. 61. 61. 61. 61. 81. 81. 41. 41. 41. 41. 91, 91, 91.

Zi. 21. 21. 91. 91.

18

So.

80 18 18 18 19 79 19 20 20 21 78 '21 22 22

23

28 28

27 27

28

28

28

29

29

40 41 42 43 44 44 45 46 46 47 47 48 48 49 49 50 50 51 52

45 45 46

46

47

47 48 49 50

97 98 100 103 104 106 107 109 110 112 113 114 115 116 118 119 121 123 124 100102104 106 108 110 111 113 114 115│1*17│1*181°19′121 122│1°24′125 127 129

93 95 96 99 101 102 104 106 107 108 109 110 111 112 114 115 117 118 1 20

110

113

114

116

166, 86,

46.

96.

6.

z6.

06.

88.

48.

110,

100, 166,

86,

46,

96,

96,

10.166,

86,

96,

6. 6. z6. 16, 06. 68. 48.

48. 98. 8. g. Eg.

£6.

z6. 16. 06.

70 71 72 74 75 77 78 79 80 81

73 74 75 77 78 80 81 82 83 84 84 86 87 88 89

83

84

85

87

81

64.

84.

52

51

L.

EL.

OL.

89.

49.

14.

69.

49.

99.

S9.

04. 89.

49.

99.

9.

9.

19.

65.

89. 89.

19.

09.

69. 49. 99. SS.

19

29.

29.

19.

09.

69.

89.

SS.

ES.

62

Table for correcting Longitude—(continued).

Change of Longitude in miles, due to a change of one mile of Latitude.

72 42 43 44 44 45

46 47

48

58 60 61

60 61
63
•65

71

64

61

60

59

49 50 51 52 53 54 55 57

57 59 60

61

45 45 46 47 48 49 50 52 52 53 54 55 56 57 59 60 62 63 65 67 69 70 *47 48 49 50 51 52 52 54 55 56 57 58 59 61 62 64 65 67 69 71 73 69 50 51 52 52 53 54 55 56 62 64 66 67 69 70 72 75 77 68 53 53 54 55 56 57 58 59 60 62 63 64 66 67 69 71 72 74 76 78 81 67 55 56 57 58 59 60 61 62 63 65 66 67 69 71 72 74 76 78 80 82 85 66 58 59 60 61 62 63 64 65 66 68 69 71 72 74 76 78 80 82 84 86 89 65 61 62 63 64 65 66 67 68 70 71 72 74 76 78 79 81 83 86 88 90 93 64 65 66 67 68 69 70 71 73 74 76 77 79 81 83 85 87 89 92 95 98 63 67 68 69 70 71 72 73 75 76 78 79 81 83 85 87 89 91 94 96 99 102 62 70 71 72 73 74 75 77 78 80 81 83 84 86 88 90 93 95 97 100 103 106 72 73 74 76 77 78 80 81 83 85 86 88 90 92 94 96 99 102 105 108 III 75 76 77 79 80 81 83 85 86 88 90 92 94 96 98 101 103 106 109 1*121*15 79 80 81 82 83 85 87 89 '90 92 94 96 98 100 102 105 107 1101 13 117 120 58 82 83 84 85 *87 88 90 92 93 95 97 99 101 104 106 109 112 115 118 121 125 85 86 87 89 90 92 94 95 97 99 101 103 105 108 111 113 116 1*191*23 126 1*30 88 89 91 92 94 95 97 99 101 103 105 107 109 112 115 117 120 124 127 131 135 91 93 94 96 97 99 101 103 105 107 109 111 113 1161*191*22 125 1291*321*36 1*40 95 96 98 99 101 103 105 107 109 1*111*131*15 1*18 121 1 24 1 27 130 133 137 141 145 '98 100 101 103 105 107 109 1*111*131*151 171 20 122 125 1 28 1*31 135 138 142 1'46 1'51 52 102 103 105 1'07 1'09 1'111'12 115 117 1*191*22 1 24 1 27 1 301 33 1 36 1 40 144 147 152 1'56 51 106 107 109 1'111'13 115 117 119 121 123 126 129 1311 351 38 141 145 1 491*53 1'57 162 50 109 1'111'13 1'15 1'17 1*191*21 1'23 1 25 1*28 1*30 1*33 136 139 1 431 46 150 154 158 163 168 49 113 115 117 119 121 1 23 1 25 1 27 1 301 321 351*38 141 144 148 151 155 159 164 169 174 48117 119 121 123 125 1*27 1*30 1*321 351 371 40 143 146 149 153 1'57 161 165 170 175 180 47 122 123 1′251′27 1°301 321 34 1 371 39 1 421 451 48 151 155 159 163 1*67 171 176 181 186 46 1 26 1 28 1 301 32 1*341*371*39 1'42 144 147 1501 53 1'57 160 164 168 173 177 1.82 188 193 45 ′30 1°32′ 1*35 1°37′1°39′ 1°41 1°44′1°47′1°49│1°52′1°56′1*591*621*661°70 1‍74 1*79 1*84 1*89│1942.00

57

56

55

54

53

See Notes upon page 272 on use of these tables.

Notes on preceding Table by Lieut. J. F. Stuart, R.N., for correcting Longitude by Chronometer for error due to having used an approximate Latitude.