No attempt is made here to explain by means of elaborate diagrams. It is believed that if the reason of things, and the principle of action, is clear, the particulars may be easily studied by any reader who is disposed to master mechanical details. THE AGE OF STEEL In very recent times the processes of civilization have had a strong and almost unnoted tendency toward the increased use of the _best_. Thus, most that iron once was, in use and practice, steel now is. This use, growing daily, widens the scope that must be taken in discussing the features of an Age of Steel. One name has largely supplanted the other. In effect iron has become steel. Had this chapter been written twenty, or perhaps ten, years earlier, it should have been more appropriately entitled the Age of Iron. A separation of the two great metals in general description would be merely technical, and I shall treat the subject very much as though, in accordance with the practical facts of the case, the two metals constituted one general subject, one of them gradually supplanting the other in most of the fields of industry where iron only was formerly used. The greatest progresses of the race are almost always unappreciated at the time, and are certainly undervalued, except by contrast and comparison. We must continually turn backward to see how far we have gone. An individual who is born into a certain condition thinks it as hard as any other until by experience and comparison he discovers what his times might have been. As for us, in the year 1894, we are not compelled to look backward very far to observe a striking contrast. [Illustration: IN OLD TIMES. PRYING OUT A "BLOOM."] All the wealth of today is built upon the forests and prairies and swamps of yesterday, and we must take a wider and more comprehensive glance backward if we should wish to institute those comparisons which make contrasts startling.