11. The Perhapsatron used a toroidal tube made in the local glass shop. 12. The shape often used is a toroidal or doughnut-shaped ferrite core. 13. A drawback of toroidal transformer construction is the higher labor cost of winding. 14. A toroidal Universe could behave like a normal Universe with periodic boundary conditions. 15. It is toroidal , which means it can be embedded on a torus. 16. Toroidal groups play an important part in the theory of compact Lie groups.17. One design uses water sprayed from a nozzle facing a toroidal charged electrode. 18. Compact toroid concepts are generally less well developed than those of toroidal machines. 19. Parson's model of the atom inspired several other toroidal ring models. 20. The term " toroid " Is also used to describe a toroidal polyhedron.
