According to Eneström, this includes a derivation of important theorems on the theory of curves in space (for example, on the angle of elevation of the tangents and the radius of curvature, as well as the equation of the bending plane), as well as Euler's definition the spherical trigonomety.
Original Source Citation
Acta Academiae Scientiarum Imperialis Petropolitanae, Volume 1782: I, pp. 19-57.
Opera Omnia Citation
Series 1, Volume 28, pp.348-381.