Metal roofs may rightly be termed modern roofs. Lead was the first of these to be introduced; copper, zinc, and galvanized iron followed. Lead and copper were used in medieval times for covering roofs, but it was not until about 17G0 that they came to be used as a general covering for large buildings.

Wood shingles and slate were known at an early period, and were used in the form of slabs having considerable weight. Edward II gave an order, in 1314 A. D., to replace the shingle roofs of certain government buildings with slate, thus showing that, even at that time, both were extensively used, though it is commonly supposed that wooden shingles are of a very much later date.

Tin, the most extensively used roof covering in the United States, was originally a North German product, and was made there as early as 1600; it next was made in Bohemia, 1020; at Pontypool, England, in 1670; and at Mausvaux, France, in 1714; but not until recently, in the United States. England produces at the present time 90 per cent. of all that is manufactured.

8. In the following pages, the different styles, methods, and materials used for roofing, as well as the application of each to the particular form or style of roof to which it is best adapted, will be discussed in the order of their importance and historical development.