Diagram, coreless vortex by W [William] Thomson A simple diagram in pencil showing the motion of water in a coreless vortex. A caption to the engraver reads 'The blue represents water. It is to be shown by very faint shading.' Subject: Physics / Fluid dynamics A print of this diagram was published in volume 42 of the Proceedings of the Royal Society as 'On the formation of coreless vortices by the motion of a solid through an inviscid incompressible fluid'. 1887