Bobbin box belonging to a Northrop single-shuttle 'S' loom with automatic bobbin insertion, 1939.
The successive inventions of devices for automatically replenishing the weft was the most important step in loom development since the invention of the power loom. Whenever the shuttle runs short of weft a full bobbin from the rotary battery is automatically inserted. A feeler passes through a hole in the left hand shuttle box. If it detects the bobbin as nearly empty the changeover mechanism is actuated when the bobbin reaches the right hand shuttlebox. The loom automatically stops on weft or warp breakage, or if the shuttle is not positioned correctly. One man could look after up to 48 looms of this type. A sample of cloth produced on this loom is at B/S21C/PP16/03