The Argand lamp is generally employed in lighthouses.  It was the greatest advance in artificial lighting until the introduction of gas. It was discovered by Monsieur Argand, a citizen of Geneva.  He was trying experiments with a common lamp he had invented.  A younger brother describes its accidental discovery.  He says: "My brother had long been trying to bring his lamp to perfection.  The neck of a broken flask was lying on the chimney-piece.  I happened to reach across the table, and to place it over the circular flame of the lamp.  Immediately it rose with brilliancy.  My brother started from his seat in ecstasy, rushed upon me in a transport of joy, and embraced me with rapture." Thus was the new form of lamp discovered.