THE IDEAL DISTANCE FOR PRECISE LEVELLING

Abstract

In order to minimize errors in Precise Levelling it is usual to stipulate a maximum distance at which a staff shall be held from the instrument. The determination of such a distance must result from a compromise between the demands of accuracy and economy, and this distance must of course fall between the lower limit, when because of nearness the instrument cannot be focussed on the staff, and the upper limit, above which the staff cannot be read distinctly.