An error in the measurement of angle causes error in direction as well as in the computed value of distance. Thus, it is important for a surveyor to:
(1) visualize the effect of errors in terms of both angle and distance,
(2) appreciate what degree of care must be exercised to keep certain errors within specified limits, and
(3) know under what conditions various errors can be eliminated. Errors in transit work may be instrumental, personal or natural.