17th century Nuremberg Ivory Diptych sundial showing latitudes for different cities, Italian hours, Babylonian hours, and the number of hours of daylight and darkness (inventory no. 7899, The Collection of Historical Scientific Instruments, Harvard Univer Happenings: Author Kevin Birth To Lecture At The Horological Society Of New York Happenings: Author Kevin Birth To Lecture At The Horological Society Of New York nuremberg dial