@ARTICLE{Skórczyński_Aleksander_The_2001, author={Skórczyński, Aleksander}, volume={vol. 50}, number={No 2}, journal={Geodesy and Cartography}, pages={91-98}, howpublished={online}, year={2001}, publisher={Polska Akademia Nauk/ Komitet Geodezji Polskiej Akademii Nauk; Polish Academy of Sciences / Commitee on Geodesy Polish Academy of Sciences}, abstract={The paper presents discusses a formula for the mean error m, of the refraction factor, determined basing on synchronie and bi-directional observations of vertical angles, performed for a section of trigonometric levelling. It turns out from analysis of the formula that the mean error of this factor is mostly influenced by mean errors of vertical angles and heights of distance meters and prisms over survey points. The error of a distance may be neglected; this leads to the simple working formula.}, type={Article}, title={The correct length of a sight line for determination of a refraction factor from synchronie and bi-directional observations}, URL={http://ochroma.man.poznan.pl/Content/121608/PDF-MASTER/5_GK_TOM_L_ZESZYT_2_2001_Skorczynski_Wlasciwa.pdf}, }