Grandfather’s compass from decades ago may no longer be the best selection for the hiker. The image below is of a compass made between 1910-1920. Though the dial is fairly detailed, the accuracy may be reduced due to the polarity of the magnetic needle.
In general terms, the polarity is how the magnetic needle will react to the earth’s magnetic field. Over a period of almost 100 years, the compass’ magnetic needle may not move in relation to magnetic north as it did when new; that could mean the differences of several degrees.
To prove this point take a new baseplate compass and compare the two (do not hold them near each other.) A navigator can also compare it a new compass or a location where a street or trail is known to run true north.
My recommendation then is to leave the old antique compass in a place of honor at home. It is time to consider buying a new compass.