The Mercator projection is a map projection that was widely used for navigation since loxodromes are straight lines (although great
circles are curved). The following equations place the x-axis
of the projection on the equator and the y-axis
at longitude , where is the longitude and is the latitude.

There is also a transverse form of the Mercator projection, illustrated above (Deetz and Adams 1934, Snyder 1987). It is given by the equations

(19)

(20)

(21)

(22)

(23)

where

(24)

(25)

Finally, the "universal transverse Mercator projection" is a map projection which maps the sphere into 60 zones of
each, with each zone mapped by a transverse Mercator projection with central meridian
in the center of the zone. The zones extend from S to N (Dana).