TIME MEASUREMENT HISTORY OF SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site hourglass 17th century hourglass in the Istituto e Museo di Storia della Scienza, Florence An ancient instrument to measure the passage of time. A quantity of fine, dry sand is contained in a bulb constricted at its center to a narrow neck. The device is turned so that all the sand is in the upper chamber: the time taken for the sand to trickle into the lower chamber depends on the amount of sand and on the diameter of the neck. Related categories    • TIME MEASUREMENT AND PUZZLES    • HISTORY OF SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP