Semaphore Metal Sign Semaphore signals were patented in the early 1840s and became the most widely used form of mechanical signals. This upper quadrant semaphore appeared on the railroad scene around 1900 and this sign will add color and interest to your train-room, bedroom or any wall you post it on. It will hang in any of the 3 lighted positions. Has 2 grommet holes for mounting. Made in the USA! Measures: 23 3/8” x 7”.