To make this evident, it is enough merely to mention a few comparatively recent inventions, such as the mariner's compass, the printing-press, gunpowder, the steam-engine, the power-loom, the cotton-gin, and the telegraph. To the introduction of the mariner's compass in the fourteenth century, by which sailors were made independent of landmarks and the stars, and could therefore go more boldly into the open sea, we owe the explorations of the fifteenth century that culminated in the discovery of America, and the way to India by the Cape of Good Hope. The introduction of gunpowder in the fourteenth century gave the lower and middle classes a weapon that made them equal in power with the nobles and brought about the downfall of the feudal system and the rise of modern democracies. The printing-press gave to the world the learning of the past and revolutionized social conditions. The invention of high explosives has made possible many of the great engineering works of to-day. The inventions that have made transportation and communication so easy and rapid have already done a great deal to bring nations to a better understanding of each other and thus to promote the peace of the world. Discoveries in medicine alone have had an incalculable influence on the health and prosperity of society. In fact, the study of history and an understanding of modern social and industrial conditions are impossible without a knowledge of scientific inventions and discoveries. (See pp. 87, 92.) Children naturally take an interest in what individuals have done, and it is easy to interest them in the work of men such as Watt, Stephenson, Whitney, Fulton, Morse, Edison, Marconi, and their fellows. The biographies of famous inventors should therefore be given, both as a record of what they did and as an inspiration to like achievements. HISTORY AND CONSTRUCTIVE WORK Constructive work may be used to advantage in history and civics. It gives concrete expression to some facts of history through the construction by the pupils of objects mentioned therein. In studying Indian life, the class may make in paper, wood, etc., wigwams, bows and arrows, stockades, etc.; in connection with pioneer life, they may make some of the buildings and implements used by the pioneers,--log houses, spinning-wheels, hominy blocks, Red River carts, etc.; in studying campaigns, they may make models in plasticine or clay, or on the sand table, of forts, battle-fields, etc., for example--the Plains of Abraham, Queenston Heights, Chateauguay, Plymouth Harbour; the Union Jack may be cut out and coloured. (See p. 68.) In this way the activities of the child may be made of practical use.