Meridians of longitude are shown by straight lines running up and down, perpendicular to the parallels of latitude, and the degrees and minutes of these Meridians are given on the horizontal border of the chart.
"Lectures in Navigation"
Ernest Gallaudet Draper
It makes no difference what longitude you are in for, on a Mercator chart, Meridians of longitude are all marked parallel.
"Lectures in Navigation"
Ernest Gallaudet Draper
Parallels of latitude, Meridians of longitude, the equator, etc.
"Lectures in Navigation"
Ernest Gallaudet Draper