The author of this book Capt. Sanjiv Verma had personal experience when his vessels Magnetic compass had a large error and he successfully followed the suggestion herein to minimise the compass error to approved levels
The objective of this effort is that a navigator should be able to easily bring down the compass deviations to manageable levels himself on board a ship without the need to call for a professional compass adjuster.
In our experience the most difficult part is to open the doors of the binnacle to see the correctors! Once this psychological barrier has been crossed then everything else will become absolutely simple.