to the list. ... It is notorious that MCCORMICK will have made over $2,000,000 on his reapers by the time his present patents shall have expired, and as the new Commissioner of Patents has a reputation for honesty to maintain, there is little danger that the monopoly will be renewed."

Indeed, the arguments over reaper patents from the 1840s up into the early 1860s were some of the early battles in what is sometimes called "the first patent litigation explosion." One early result was that the Patent Act of 1861 removed the discretionary power of the Patent Office to extent patents by seven years at a time, and instead created the 17-year patent term.

Innovations can take decades before coming into widespread use

Although versions of the reaper were patented inthe first half of the 1830s, they didn't come into widespread use until the 1850s and later. Why not? A body of research in economic history tackled that question several decades ago, and Rhodes provides a nice compact summary of how thinking on this question evolved:

The traditional explanation for this surge in sales was the rapid rise of global wheat prices during the Crimean War, which limited grain exports from Russia and other nations in the Black Sea region. But in the 1960s, Stanford University economist Paul David offered another primary explanation: He argued that before the mid-1850s, most American farms were simply too small to make reapers practical.

The average farm size was growing, however, as grain production shifted from the East to the Midwest, where arable land