Survey.
a method of extending a survey line by taking the average of two foresights, one with the telescope direct and one with it inverted, made each time by transiting the telescope after a backsight.
Survey.
a method of extending a survey line by taking the average of two foresights, one with the telescope direct and one with it inverted, made each time by transiting the telescope after a backsight.
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012