This is a Machine Gun Feed Belt loading machine, which as it implies loads the rounds into the cloth belt. During this period of John Browning’s machine gun designs he was using a fabric belt for feeding the rounds. Even later models like the M1919 benefited from this form of feed belt rather than metal links. The feed mechanism had a claw that would pull the rounds into the breech.
John Moses Browning applied for this patent on November 15th, 1899. He was granted US Patent 660,244 for this design on October 23rd, 1900.