Identifier: newtreatiseonpra00thomrich (find matches)
Title: A new treatise on the practice of navigation at sea : containing all the details necessary to enable the mariner to become a good practical navigator.
Year: 1902 (1900s)
Authors: Thoms, William
Subjects: Navigation Nautical astronomy
Publisher: New York : Printed for the author and sold by John Bliss & Co
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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Degrees of Longitude also decrease from the Equator towardsthe Poles. But in Mercator Sailing the Meridians are all parallel to each other, and a Degree of Longitudeis 60 miles in length, measured on the Equator, in all parts of the World. To remedy this, the Degreesof Latitu le are expanded from the Equator towards the Poles, and the miles of Latitude grow larger ; so thatin the Latitude of 60* the miles of Latitude are twice the length they are on the Equator, and the Degreeof Longitude is only 30 of these miles long ; near the Pole one mile of Latitude is nearly the length of 60miles on the Equator, and the Degree of Longitude only 1 mile long. But as the Polar Seas are not navi-gable much above 80°, Charts or Tables on this projection are rarely published beyond that paralleL DIAGRAxM OF MERCATORS SAILING, thowing the Expansion of the Parallels of Latitude for every 10 Degrees, and the Meridians (or ParalUUof Longitude) all Parallel \o each other at 10 Degrees Distance. Fio. 16.
Text Appearing After Image:
90 80 -70 60 50 40 30W E 5 T L 0 N CT ^ o io ao EAST LOnC PROJECTED BY THE FOLLOWING TABLE And the Measurements taken from the Degrees on the Equator. From the Equator to Lat. 10° the Expansion is 0° 3 From Lat 10° to 20 (( 0 25 l( 20 to 30 « 1 28 t* 30 to 40 3 43 M 40 lo 50 it 7 54 U 50 to 60 t. 15 27 « 60 to 70 ti 29 26 u 70 to 80 u 69 35 Distance of 1st Parallel from the Equate the Expansion of the miles of Latitude from the Equator towards the Poles. To find the Meridiiiiial Difference of Latitude. When the Latitudes are of the same tmme, take the differeno* of tiMMeridianal Parts for the two Latitudes. When of contrary rames, take the sum of the Meridianal Part*. 2d MERCATORS SAILING. CASE I. One Latitude and Longitude. Course and Distanit given

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