Practical Boat-Sailing: A Concise and Simple Treatise by Douglas Frazar

Author:Douglas Frazar [Frazar, Douglas]
Language: eng
Format: epub, pdf
Tags: Sailing
Published: 2012-05-26T00:00:00+00:00

Example II. (see diagram Fig. 2).—Placing the compass in front of the observer, it is found that the lighthouse bears W. by compass, and that the lightship bears S. W. by S. With these two bearings we consult the chart, and lay off the two lines by means of the parallel-rulers; and, if the chart gives the distance in miles of the lightship from the lighthouse, then, by means of a common rule of equal parts, we shall be able to measure the distance of the yacht from the lighthouse or from the lightship. At the foot of most charts, however, will be found a scale of miles, and, having once ascertained the exact position of the yacht by means of cross-bearings, it will be very easy, with a pair of dividers, to find its distance in miles from any desired object within view, or designed upon the chart, and, by the use of the parallel-rulers, the course, by compass, that should be sailed to reach any desired point.

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.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.