Error Occurs in Compass Surveying of Land | Compass Surveying| Surveying

The compass ring is graduated to half a degree but the readings can be well estimated to 15 minutes, which means that the error of reading should not exceed 7½ minutes. But due to magnetic changes and variation of declination etc., the readings can seldom be relied upon to less than 10 minutes, therefore, the permissible error per bearing should [...]