Snow was described in China, as early as 135 BCE in Han Ying's book Disconnection, which contrasted the pentagonal symmetry of flowers with the hexagonal symmetry of snow. Albertus Magnus proved what may be the earliest detailed European description of snow in 1250. Johannes Kepler attempted to explain why snow crystals are hexagonal in his 1611 book, Strena seu De Nive Sexangula. In 1675 Friedrich Martens, a German physician, catalogued 24 types of snow crystal. In 1865, Frances E. Chickering published Cloud Crystals - a Snow-Flake Album. In 1894, A. A. Sigson photographed snowflakes under a microscope, preceding Wilson Bentley 's series of photographs of individual snowflakes in the Monthly Weather Review.