The SciencesSundials and their ConstructionPart IX--The Principle and Construction of the Armillary SphereBy Margaret Walton Mayall, R. Newton Mayalll on March 1, 1935AdvertisementABOUT THE AUTHOR(S)Recent Articles by Margaret Walton MayallSundials and Their ConstructionSundials and their ConstructionSundials and their Construction--VI