Comment by WillAdams

Note that they weren't directly printed with a hot metal casting machine (I believe Monotype was used, since it output discrete letters which did not need to be sawn apart as the Line of Type the competitor used), but rather what could be composed on a hot metal casting machine was, then additional spacing material and special characters and extensions which weren't available from that keyboard were sourced and the whole put together as a composed galley, then a proof was pulled and once approved, printed, then photographed to make a negative which was then used to make an offset plate for actually printing the book.