The Parkhurst patent Cartridge Packing and Feeding Case was a device intended to be used to rapidly load the double stack Bruce Feed magazine on the Gatling Gun.
It consisted of a paper box with paper dividers and two pieces of wood dovetailed together with a thin piece of sheet metal attached to the upper wood, plus a paper lid to keep everything clean until use.
The sheet metal kept the cartridges from falling out as the case was raised to a vertical position with the base of the cartridges just above the twin openings in the magazine. As the case was lowered the upper wood/metal slid off the base of the cartridges which were now supported by the magazine which was much more rapidly filled than by loading the rounds individually by hand. The case’s scarcity may indicate it was not widely used.