10. Why is Pittsburgh called the "workshop of the world"? 11. Name two famous men of Pittsburgh and tell what they have done for the city and for the world. 12. Examine a map and find what shipping ports are within easy access of Pittsburgh. 13. Find by what route ore and other material shipped by way of the Great Lakes reach Pittsburgh. DETROIT In population, Detroit is the ninth city of the United States. In the value of its manufactured products, it is fifth. In the value of its exports, it is the leading port on the Canadian border. With these facts in mind it will be interesting to learn something of the history of Detroit; something of the goods it manufactures and the reasons for its growth and prosperity. During the years when the French governed Canada, manufacturing and agriculture played a very small part in their affairs. Their business men were chiefly interested in the fur trade; their governors were interested mainly in extending the territory over which floated the banner of their king; and the teaching of Christianity to the hordes of Indians who inhabited the country seemed of the greatest importance to their priests and missionaries. So, because it served the purpose of each, all three classes--the fur traders, the crown officers, and the missionaries--worked hand in hand in exploring and in penetrating the wilderness in every direction. They suffered every hardship, endured every privation, and very often fell victims to the cruelty of the savages. [Illustration: THE GREAT LAKES] In those days of French rule, railroads were unheard of, and wagon roads were almost as scarce. Travel was sometimes through the woods, along the trails made by the Indians; but usually it was by the water courses, over which the Indian canoes carried furs to be traded for the goods of the French. Now if you will look at a map which shows the Canadian border of the United States and follow the course of the Great Lakes, you will see that at four places their broad waters narrow into rivers or straits. These places are first, the Niagara River; second, where the waters of Lake Huron pass into Lake Erie; third, at the Sault Ste. Marie; and fourth, at the Straits of Mackinac. Between the East and the West, the Great Lakes and the St. Lawrence River formed the main artery of travel. To control the narrow rivers and straits that connect the Great Lakes was to control the travel over them, and as the French extended their rule from Quebec to the West, they fortified these narrow places one by one. Fort Niagara was built at the mouth of the Niagara River. Then on July 24, 1701, Antoine de la Mothe Cadillac landed on the banks of the Detroit River and began the work of building a palisade fort, almost where the river widens into Lake Saint Clair.