Appendix to Captain Rohde's universal sea language, or, code of signals : containing directions for giving the latitude and longitude, ships' numbers to a great extent, and a safe method of making secret signals, or such as are only to be understood in their proper sense by certain persons : likewise telegraph signals, and finally, night signals, to be made use of by vessels of all descriptions, in order to prevent the danger of collision, or running foul of each other / by L.J. Rohde