Ivory is a hard substance, not unlike bone, of which the teeth of most mammals chiefly consist, the dentine or tooth-substance which in transverse sections shows lines of different color running in circular arcs. It is used extensively for industrial purposes and is derived from the elephant, walrus, hippopotamus, narwhal, and some other animals. The ivory of the tusks of the African elephant is held in the highest estimation by manufacturers; the tusks vary in size, ranging from a few ounces in weight to 170 pounds. Holtzapffel states that he saw fossil tusks on the banks of rivers of Northern Siberia which weighed 186 pounds each. Ivory is simply tooth-substance of exceptional hardness, toughness, and elasticity, due to the firmness and regularity of the dentinal tubules which radiate from the axial pulp-cavity to the periphery of the tooth. How Did Trial by Jury Originate? ~WHY JURIES HAVE TWELVE MEN~ A jury consists of a certain number of men selected according to law and sworn to inquire into and determine facts concerning a cause or an accusation submitted to them, and to declare the truth according to the evidence. The custom of trying accused persons before a jury, as practised in this country and England, is the natural outgrowth of rudimentary forms of trial in vogue among our Anglo-Saxon ancestors. The present system of trial by jury is the result of a gradual growth under the English Common Law. There is no special reason why twelve is the usual number chosen for a complete jury except the necessity for limiting the number. In a grand jury the number according to law must not be less than twelve nor more than twenty-three, and twelve votes are necessary to find an indictment. The ancient Romans also had a form of trial before a presiding judge and a body of judices. The right of trial by jury is guaranteed by the United States Constitution in all criminal cases, and in civil cases where the amount in dispute exceeds $20. A petit or trial jury consists of twelve men, selected by lot from among the citizens residing within the jurisdiction of the court. Their duty is to determine questions of fact in accordance with the weight of testimony presented and report their finding to the presiding judge. An impartial jury is assured by drawing by lot and then giving the accused, in a criminal case, the right to dismiss a certain number without reason and certain others for good cause. Each of the jurymen must meet certain legal requirements as to capacity in general and fitness for the particular case upon which he is to sit, and must take an oath to decide without prejudice and according to the testimony. A coroner’s jury or jury of inquest is usually composed of from six to fifteen persons, summoned to inquire into the cause of sudden or unexplained deaths. Can Animals Foretell the Weather?