Iron when heated expands. For example, if a piece of stock 12 by 1 by ⁵⁄₁₉ in. is heated red its entire length and then measured, it will be about 12¼ in. long. When the piece is cooled it will go back to its original length of twelve inches.
In making bands or tires for wagons, they are made a little short, then heated and put on, letting them shrink to their original size, which makes them tight.
Wrought Iron Lantern.
CHAPTER VI.
Marking Tongs—Pig Iron—Puddling—The Bessemer Process—The Open Hearth Process—Crucible Steel—The Cementation Process—Tempering.
Exercise No. 16.
In forging tongs, stock ⅞-in. square of Norway or Swedish iron may be used, as it is much easier for a beginner in welding the handle on to the jaws. Soft steel may be used later on if desired. [Figure 100] shows the drawing of a finished pair of flat tongs. [Figure 101] shows the size of stock used and the dimensions of the rough forgings. It is not intended that the dimensions given are to be accurately followed, but they are given as an idea of what may be forged from this size of stock. In forging the jaws, no helper is required to handle a sledge hammer after the piece is cut from the bar for the reason that it is time lost for the one who handles it, besides one man can do it.
