... the orders of a mysterious and invisible chief, a sort of arch-fiend on earth who has appropriately taken to himself the name of the Prinoe of Darkness, saving only that be has spelt it backwards. Who is this invisible and mysterious being, or is he only ...

... course, forgetting Louis Holt, at once shut himself up in his laboratory by the turbine, and for the next four hours remained invisible, preparing • large supply of his motor pass and pumping them into the exhausted cylinders of the Marie), and all the others ...