To get the true bearing of the same object you must make the proper corrections for Variation and Deviation.
"Lectures in Navigation"
Ernest Gallaudet Draper
In order to change it into the compass course of your ship, you must make the proper corrections for the compass error, i.
"Lectures in Navigation"
Ernest Gallaudet Draper
The corrections, notes, and other data were also no longer needed; all my observations had been reduced, and the corrections were valuable only for a future re-examination.
"My Attainment of the Pole"
Frederick A. Cook