This is pretty self-explanatory. Those are some big staples the Government Printing Office used here.
Music books tend to want to be 9″ x 12″ and square back wire stitched is a not uncommon format for them. The Watkiss system can make a book from 8 to 200 pages. The machine is patented by Watkiss, a British company. (See the comment from Jo Watkiss on the previous post.)