There was a total of 347 military treatises written during the Song period, as listed by the history text of the "Song Shi" (compiled in 1345). However, only a handful of these military treatises have survived, which includes the "Wujing Zongyao" written in 1044. It was the first known book to have listed formulas for gunpowder; it gave appropriate formulas for use in several different kinds of gunpowder bombs. It also provided detailed descriptions and illustrations of double-piston pump flamethrowers, as well as instructions for the maintenance and repair of the components and equipment used in the device.