Mobius must be regarded as one of the leaders in the introduction of the powerful methods of modern projective geometry.

His manual on Graphical Statics and his Elements of Projective Geometry (translated by C. Leudesdorf), have been published in English by the Clarendon Press.

In projective geometry it may be defined as the conic which intersects the line at infinity in two real points, or to which it is possible to draw two real tangents from the centre.

It was during his imprisonment here that, "prive de toute espece de livres et de secours, surtout distrait par les malheurs de ma patrie et les miens propres," as he himself puts it, he began his researches on projective geometry which led to his great treatise on that subject.

Analytic This is the analytical expression of the projective Geometry.