A TABLE SHOWING, FOR SEVERAL DEGREES OF LATITUDE, HOW MANY MILES DISTANT THE TWO MERIDIANS ARE WHOSE DIFFERENCE OF LONGITUDE IS ONE DEGREE.
| Lat. | Miles. | Lat. | Miles. | Lat. | Miles. | Lat. | Miles. |
| 15 | 57.96 | 26 | 53.93 | 37 | 47.92 | 48 | 40.15 |
| 16 | 57.68 | 27 | 53.46 | 38 | 47.28 | 49 | 39.36 |
| 17 | 57.38 | 28 | 52.98 | 39 | 46.63 | 50 | 38.57 |
| 18 | 57.06 | 29 | 52.48 | 40 | 45.96 | 51 | 37.76 |
| 19 | 56.73 | 30 | 51.96 | 41 | 45.28 | 52 | 36.94 |
| 20 | 56.38 | 31 | 51.43 | 42 | 44.59 | 53 | 36.11 |
| 21 | 56.01 | 32 | 50.88 | 43 | 43.88 | 54 | 35.27 |
| 22 | 55.63 | 33 | 50.32 | 44 | 43.16 | 55 | 34.41 |
| 23 | 55.23 | 34 | 49.74 | 45 | 42.43 | 56 | 33.55 |
| 24 | 54.81 | 35 | 49.15 | 46 | 41.68 | 57 | 32.68 |
| 25 | 54.38 | 36 | 48.54 | 47 | 40.92 | 58 | 31.80 |
TABLE FOR DETERMINING THE DISTANCE THAT OBJECTS AT SEA CAN BE SEEN IN STATUTE MILES.
Note.—Enter the table in the column of height in feet, which represents the height of the observer above the sea; and opposite to it, in the column of miles, will be the result.
Column [A]: Height in Feet.
Column [B]: Miles.
| [A] | [B] | [A] | [B] | [A] | [B] | [A] | [B] | [A] | [B] | [A] | [B] |
| 1 | 1.32 | 13 | 4.77 | 25 | 6.61 | 37 | 8.05 | 49 | 9.26 | 105 | 13.56 |
| 2 | 1.87 | 14 | 4.95 | 26 | 6.75 | 38 | 8.16 | 50 | 9.35 | 110 | 13.88 |
| 3 | 2.29 | 15 | 5.12 | 27 | 6.87 | 39 | 8.26 | 55 | 9.81 | 115 | 14.19 |
| 4 | 2.65 | 16 | 5.29 | 28 | 7.00 | 40 | 8.37 | 60 | 10.25 | 120 | 14.49 |
| 5 | 2.96 | 17 | 5.45 | 29 | 7.12 | 41 | 8.47 | 65 | 10.67 | 125 | 14.79 |
| 6 | 3.24 | 18 | 5.61 | 30 | 7.25 | 42 | 8.57 | 70 | 11.07 | 130 | 15.08 |
| 7 | 3.50 | 19 | 5.77 | 31 | 7.37 | 43 | 8.68 | 75 | 11.46 | 135 | 15.37 |
| 8 | 3.74 | 20 | 5.92 | 32 | 7.48 | 44 | 8.78 | 80 | 11.83 | 140 | 15.65 |
| 9 | 3.97 | 21 | 6.06 | 33 | 7.60 | 45 | 8.87 | 85 | 12.20 | 145 | 15.93 |
| 10 | 4.18 | 22 | 6.21 | 34 | 7.71 | 46 | 8.97 | 90 | 12.55 | 150 | 16.20 |
| 11 | 4.39 | 23 | 6.34 | 35 | 7.83 | 47 | 9.07 | 95 | 12.89 | 160 | 16.73 |
| 12 | 4.58 | 24 | 6.48 | 36 | 7.94 | 48 | 9.17 | 100 | 13.23 | 170 | 17.25 |
Example I.—Sailing along in the yacht "Firefly," from the top of the house on which I was standing, which brought my eyes to about 12 feet above the level of the sea, I observed seaward the head of a gaff-topsail that evidently belonged to a yacht of about ten tons, and was therefore estimated to be about 45 feet from the level of the sea. How far were these vessels from each other?
In the table,
| Opposite 12 feet stands | 4.58 miles | |
| Opposite 45 feet stands | 8.87 | |
| —— | ||
| Distance apart | 13.45 miles |