Vector which is perpendicular to said surface or manifold. In a inner product space, the inner product of the normal vector with all vectors which comprise the surface is 0.
... Pencil Museum[?], Keswick
Dock Museum[?], Barrow-in-Furness[?]
Kendal Museum[?]
Museum of Lakeland Life[?], Kendal[?]
Tullie House Museum, Carlisle
Derby and ...