Category: How To ...
How to Succeed as an Inventor Showing the Wonderful Possibilities in the Field of Invention; the Dangers to Be Avoided; the Inventions Needed; How to Perfect and Develop New Ideas to the Money Making Stage
Pig iron is worth $20 per ton; Made into horse shoes, $90; into knife blades, $200; into watch springs, $1000; that is, raw iron, $20, brain power, $980.--Newell Dwight Hillis.