My wife and I were doing an acrostic puzzle in which one of the clues was “penny farthing” and the answer they wanted was “bicycle.” I had never heard the term, so I looked it up, and it has a wonderful explanation. OED:
A bicycle with a large front wheel and a small rear one, current from the early 1870s to the mid 1890s; an ordinary. Now hist.
[…]1910 Lotinga’s Weekly 7 May 64 The old type of machine, known as the ‘Penny-Farthing’ owing to the size of the wheels.
The Wikipedia article has a picture showing the two coins together, as well as one of the contraption itself.