  Nematics with a broken polar symmetry is one of the fascinating recent
discoveries in the field of soft matter. High spontaneous polarisation and the
fluidity of the ferroelectric nematic $N_{\mathrm{F}}$ phase make such
materials attractive for future applications and interesting for fundamental
research. Here we explore the polar and mechanical properties of a
room-temperature ferroelectric nematic and its behaviour in a magnetic field.
We show that $N_{\mathrm{F}}$ is much less susceptible to the splay deformation
than to the twist. The strong splay rigidity can be attributed to the
electrostatic self-interaction of the polarisation avoiding the polarisation
splay.
