"Crossed flags" have been used by the Signal Corps since 1864, when they were prescribed for wear on the uniform coat by enlisted men of the Signal Corps. In 1884, a burning torch was added to the insignia and the present design adopted on 1 July of that year. The flags and torch are symbolic of signaling or communication. Two signal flags crossed, dexter flag- the flag on the right, white with red center, the sinister flag on the left, red with white center, staffs of gold, with a flaming torch of gold color upright at center of crossed flags. Branch colors: Orange trimmings and facings were approved for the Signal Service in 1872. The white piping was added in 1902, to conform to the custom which prevailed of having piping of a different color for all except the line branches.
Click photo to enlarge for history of the wigwag.