It is often useful to know how many geographical or nautical miles, which measure at the equator 6,086.4 feet in length, are contained in a degree of longitude at different latitudes; that is to say, a degree of longitude east or west of 89° N. latitude is only 1.05 nautical mile in length; and yet, in another sense, this 1.05 is 60 miles, or one degree in length: hence the following table:--
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.
+---+-----+---+-----+---+-----+---+-----+---+-----+---+-----+ |[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| +---+-----+---+-----+---+-----+---+-----+---+-----+---+-----+