Mark Twain was, in the esti­ma­tion of many, the Unit­ed States of Amer­i­ca's first tru­ly home­grown man of let­ters. And in keep­ing with what would be rec­og­nized as the can-do Amer­i­can spir­it, he could­n't resist putting him­self forth now and again as a man of sci­ence - or, more prac­ti­cal­ly, a man of tech­nol­o­gy. Here on Open Cul­ture, we've pre­vi­ous­ly fea­tured his patent­ed inven­tions (includ­ing a bet­ter bra strap), the type­writer of which he made pio­neer­ing use to write a book,