C849 He Had to Send a Letter

Feng Changge couldn't be sure if the mechanical bird would deliver the message. The letter was dusted with phosphorus powder, which would ignite at normal temperatures. If Yue Jinglou discovered it, the letter would burn automatically, leaving no trace.

Feng Changge worried whether Yue Jingchen would receive the letter at all. The phosphorus could be blown away by the wind